Tests and fixes for double-enumeration on AddRange and adding of null to PopsicleList
diff --git a/src/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj b/src/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj
index 95ab0b9..f87546f 100644
--- a/src/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj
+++ b/src/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj
@@ -97,6 +97,7 @@
     <Compile Include="Descriptors\MessageDescriptorTest.cs" />

     <Compile Include="DynamicMessageTest.cs" />

     <Compile Include="ExtendableMessageTest.cs" />

+    <Compile Include="GeneratedBuilderTest.cs" />

     <Compile Include="GeneratedMessageTest.cs" />

     <Compile Include="MessageStreamIteratorTest.cs" />

     <Compile Include="MessageStreamWriterTest.cs" />