Add s4 docs

.gitignore

@@ -2,3 +2,5 @@ venv/
 build/
 *.swp
 *.*~
+*.iml
+.idea/

README.rst

@@ -7,9 +7,14 @@ documentation is created using Sphinx_.
 Requirements to build the documentation are:
 
 * Sphinx_, obviously.
-* The javasphinx_ extension for Sphinx.
 * LaTeX, if you want to create a PDF version of the documentation.
 
+e.g. on Ubuntu:
+
+    pip3 install -U Sphinx
+
+    sudo apt install latexmk
+
 If you want to creat the HTML documentation using the lovely `RTD theme`_ you
 will need to install this as well:
 

exts/javaext/__init__.py

@@ -0,0 +1,25 @@
+#
+# Copyright 2012-2015 Bronto Software, Inc. and contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+from .domain import JavaDomain
+from .extdoc import javadoc_role
+
+
+def setup(app):
+    app.add_domain(JavaDomain)
+
+    app.add_config_value('javadoc_url_map', dict(), '')
+    app.add_role('java:extdoc', javadoc_role)