Restructure the Protos directory.

"upstream/" is now a copy of the files protocolbuffers/protobuf, this is
basically moving the "google/protobuf" and "conformance" directories just down a
level, but it will hopefully make things a little more clear.

All the _local_ .proto files for other purposes are now moved into sub
directories that match the name of their directories in "Sources/" or "Tests/".

The places were SwiftProtobuf was using upstream files for tests, those files
have now been forked. So they exist within "Protos/SwiftProtobufTests/" but they
will *no* longer be updated to match upstream. This is a *good* thing as in the
past there have been build breaks with upstream changed and it broke the test.
Now the files are specific to this project and any edits desired can be made.
NOTE: At some point the files should get updated/reduced down to only what is
needed because they have always had some extra message/enums/fields that the
local tests didn't need, and so the simplification would likely be good.

Lastly, a few upstream .proto files are now mirrored from "Protos/upstream/" in
to the specific project level directory needed (SwiftProtobuf, Conformance,
etc.). This gets the files clearly in a target directory where they are used,
but does mean they have to be updated in this second location. Symlinks might
have worked for this, but to avoid issues building the package on any platform
(Windows?), the copies were used instead.

The "Reference/" directory was then update to mirror this new layout.

Protos/SwiftProtobufTests/map_proto2_unittest.proto

@@ -0,0 +1,125 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+import "unittest_import.proto";
+
+option cc_enable_arenas = true;
+
+// We don't put this in a package within proto2 because we need to make sure
+// that the generated code doesn't depend on being in the proto2 namespace.
+// In map_test_util.h we do "using namespace unittest = protobuf_unittest".
+package protobuf_unittest;
+
+enum Proto2MapEnum {
+  PROTO2_MAP_ENUM_FOO = 0;
+  PROTO2_MAP_ENUM_BAR = 1;
+  PROTO2_MAP_ENUM_BAZ = 2;
+}
+
+enum Proto2MapEnumPlusExtra {
+  E_PROTO2_MAP_ENUM_FOO = 0;
+  E_PROTO2_MAP_ENUM_BAR = 1;
+  E_PROTO2_MAP_ENUM_BAZ = 2;
+  E_PROTO2_MAP_ENUM_EXTRA = 3;
+}
+
+message TestEnumMap {
+  map<int32, Proto2MapEnum> known_map_field = 101;
+  map<int32, Proto2MapEnum> unknown_map_field = 102;
+
+  // Other maps with all key types to test the unknown entry serialization
+  map<int64, Proto2MapEnum> unknown_map_field_int64 = 200;
+  map<uint64, Proto2MapEnum> unknown_map_field_uint64 = 201;
+  map<int32, Proto2MapEnum> unknown_map_field_int32 = 202;
+  map<uint32, Proto2MapEnum> unknown_map_field_uint32 = 203;
+  map<fixed32, Proto2MapEnum> unknown_map_field_fixed32 = 204;
+  map<fixed64, Proto2MapEnum> unknown_map_field_fixed64 = 205;
+  map<bool, Proto2MapEnum> unknown_map_field_bool = 206;
+  map<string, Proto2MapEnum> unknown_map_field_string = 207;
+  map<sint32, Proto2MapEnum> unknown_map_field_sint32 = 208;
+  map<sint64, Proto2MapEnum> unknown_map_field_sint64 = 209;
+  map<sfixed32, Proto2MapEnum> unknown_map_field_sfixed32 = 210;
+  map<sfixed64, Proto2MapEnum> unknown_map_field_sfixed64 = 211;
+}
+
+message TestEnumMapPlusExtra {
+  map<int32, Proto2MapEnumPlusExtra> known_map_field = 101;
+  map<int32, Proto2MapEnumPlusExtra> unknown_map_field = 102;
+
+  // Other maps with all key types to test the unknown entry serialization
+  map<int64, Proto2MapEnumPlusExtra> unknown_map_field_int64 = 200;
+  map<uint64, Proto2MapEnumPlusExtra> unknown_map_field_uint64 = 201;
+  map<int32, Proto2MapEnumPlusExtra> unknown_map_field_int32 = 202;
+  map<uint32, Proto2MapEnumPlusExtra> unknown_map_field_uint32 = 203;
+  map<fixed32, Proto2MapEnumPlusExtra> unknown_map_field_fixed32 = 204;
+  map<fixed64, Proto2MapEnumPlusExtra> unknown_map_field_fixed64 = 205;
+  map<bool, Proto2MapEnumPlusExtra> unknown_map_field_bool = 206;
+  map<string, Proto2MapEnumPlusExtra> unknown_map_field_string = 207;
+  map<sint32, Proto2MapEnumPlusExtra> unknown_map_field_sint32 = 208;
+  map<sint64, Proto2MapEnumPlusExtra> unknown_map_field_sint64 = 209;
+  map<sfixed32, Proto2MapEnumPlusExtra> unknown_map_field_sfixed32 = 210;
+  map<sfixed64, Proto2MapEnumPlusExtra> unknown_map_field_sfixed64 = 211;
+}
+
+message TestImportEnumMap {
+  map<int32, protobuf_unittest_import.ImportEnumForMap> import_enum_amp = 1;
+}
+
+message TestIntIntMap {
+  map<int32, int32> m = 1;
+}
+
+// Test all key types: string, plus the non-floating-point scalars.
+message TestMaps {
+  map<int32, TestIntIntMap> m_int32 = 1;
+  map<int64, TestIntIntMap> m_int64 = 2;
+  map<uint32, TestIntIntMap> m_uint32 = 3;
+  map<uint64, TestIntIntMap> m_uint64 = 4;
+  map<sint32, TestIntIntMap> m_sint32 = 5;
+  map<sint64, TestIntIntMap> m_sint64 = 6;
+  map<fixed32, TestIntIntMap> m_fixed32 = 7;
+  map<fixed64, TestIntIntMap> m_fixed64 = 8;
+  map<sfixed32, TestIntIntMap> m_sfixed32 = 9;
+  map<sfixed64, TestIntIntMap> m_sfixed64 = 10;
+  map<bool, TestIntIntMap> m_bool = 11;
+  map<string, TestIntIntMap> m_string = 12;
+}
+
+// Test maps in submessages.
+message TestSubmessageMaps {
+  optional TestMaps m = 1;
+}
+
+message TestProto2BytesMap {
+  map<int32, bytes> map_bytes = 1;
+  map<int32, string> map_string = 2;
+}

Protos/SwiftProtobufTests/map_unittest.proto

@@ -0,0 +1,126 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto3";
+
+option cc_enable_arenas = true;
+
+import "unittest.proto";
+
+// We don't put this in a package within proto2 because we need to make sure
+// that the generated code doesn't depend on being in the proto2 namespace.
+// In map_test_util.h we do "using namespace unittest = protobuf_unittest".
+package protobuf_unittest;
+
+// Tests maps.
+message TestMap {
+  map<int32, int32> map_int32_int32 = 1;
+  map<int64, int64> map_int64_int64 = 2;
+  map<uint32, uint32> map_uint32_uint32 = 3;
+  map<uint64, uint64> map_uint64_uint64 = 4;
+  map<sint32, sint32> map_sint32_sint32 = 5;
+  map<sint64, sint64> map_sint64_sint64 = 6;
+  map<fixed32, fixed32> map_fixed32_fixed32 = 7;
+  map<fixed64, fixed64> map_fixed64_fixed64 = 8;
+  map<sfixed32, sfixed32> map_sfixed32_sfixed32 = 9;
+  map<sfixed64, sfixed64> map_sfixed64_sfixed64 = 10;
+  map<int32, float> map_int32_float = 11;
+  map<int32, double> map_int32_double = 12;
+  map<bool, bool> map_bool_bool = 13;
+  map<string, string> map_string_string = 14;
+  map<int32, bytes> map_int32_bytes = 15;
+  map<int32, MapEnum> map_int32_enum = 16;
+  map<int32, ForeignMessage> map_int32_foreign_message = 17;
+  map<string, ForeignMessage> map_string_foreign_message = 18;
+  map<int32, TestAllTypes> map_int32_all_types = 19;
+}
+
+message TestMapSubmessage {
+  TestMap test_map = 1;
+}
+
+message TestMessageMap {
+  map<int32, TestAllTypes> map_int32_message = 1;
+}
+
+// Two map fields share the same entry default instance.
+message TestSameTypeMap {
+  map<int32, int32> map1 = 1;
+  map<int32, int32> map2 = 2;
+}
+
+enum MapEnum {
+  MAP_ENUM_FOO = 0;
+  MAP_ENUM_BAR = 1;
+  MAP_ENUM_BAZ = 2;
+}
+
+// Test embedded message with required fields
+message TestRequiredMessageMap {
+  map<int32, TestRequired> map_field = 1;
+}
+
+message TestArenaMap {
+  map<int32, int32> map_int32_int32 = 1;
+  map<int64, int64> map_int64_int64 = 2;
+  map<uint32, uint32> map_uint32_uint32 = 3;
+  map<uint64, uint64> map_uint64_uint64 = 4;
+  map<sint32, sint32> map_sint32_sint32 = 5;
+  map<sint64, sint64> map_sint64_sint64 = 6;
+  map<fixed32, fixed32> map_fixed32_fixed32 = 7;
+  map<fixed64, fixed64> map_fixed64_fixed64 = 8;
+  map<sfixed32, sfixed32> map_sfixed32_sfixed32 = 9;
+  map<sfixed64, sfixed64> map_sfixed64_sfixed64 = 10;
+  map<int32, float> map_int32_float = 11;
+  map<int32, double> map_int32_double = 12;
+  map<bool, bool> map_bool_bool = 13;
+  map<string, string> map_string_string = 14;
+  map<int32, bytes> map_int32_bytes = 15;
+  map<int32, MapEnum> map_int32_enum = 16;
+  map<int32, ForeignMessage> map_int32_foreign_message = 17;
+}
+
+// Previously, message containing enum called Type cannot be used as value of
+// map field.
+message MessageContainingEnumCalledType {
+  enum Type {
+    TYPE_FOO = 0;
+  }
+  map<string, MessageContainingEnumCalledType> type = 1;
+}
+
+// Previously, message cannot contain map field called "entry".
+message MessageContainingMapCalledEntry {
+  map<int32, int32> entry = 1;
+}
+
+message TestRecursiveMapMessage {
+  map<string, TestRecursiveMapMessage> a = 1;
+}