Reviving support for instrumentation in CSharpCodeVisitor

Fixes #42
From my comment earlier, it looks like when you pasted this in it auto-formatted some of the blocks which may be the reason why some of the generated numbers don't line up:

http://aspnetwebstack.codeplex.com/SourceControl/latest#test/System.Web.Razor.Test/TestFiles/CodeGenerator/CS/Source/Instrumented.cshtml