THRIFT-2015 Thrift exceptions should derive from TException

Patch: Jens Geyer
diff --git a/lib/csharp/src/Thrift.csproj b/lib/csharp/src/Thrift.csproj
index cb264c8..439b960 100644
--- a/lib/csharp/src/Thrift.csproj
+++ b/lib/csharp/src/Thrift.csproj
@@ -105,6 +105,7 @@
     <Compile Include="Server\TServer.cs" />

     <Compile Include="Server\TSimpleServer.cs" />

     <Compile Include="Server\TThreadPoolServer.cs" />

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

     <Compile Include="TApplicationException.cs" />

     <Compile Include="TProcessor.cs" />

     <Compile Include="Transport\TBufferedTransport.cs" />