Fix encoding of serialized paths (frozen string error)

lib/yard/serializers/yardoc_serializer.rb

@@ -77,7 +77,7 @@ def serialized_path(object)
               p.gsub(/[^\w\.-]/) do |x|
                 encoded = '_'
 
-                x.each_byte {|b| encoded << ("%X" % b) }
+                x.each_byte {|b| encoded += ("%X" % b) }
                 encoded
               end
             end.join('/') + '.' + extension

spec/serializers/yardoc_serializer_spec.rb

@@ -45,6 +45,18 @@ class YARD::Serializers::YardocSerializer
     end
   end
 
+  describe "#serialized_path" do
+    it "handles String path name" do
+      path = @serializer.serialized_path('Path::To#object')
+      expect(path).to eq('objects/Path/To/object_i.dat')
+    end
+
+    it "handles special encoding characters" do
+      path = @serializer.serialized_path('object$')
+      expect(path).to eq('objects/object_24.dat')
+    end
+  end
+
   describe "#lock_for_writing" do
     it "creates a lock file during writing and cleans up" do
       expect(File).to receive(:open!).with(@serializer.processing_path, 'w')