CSharpProjectContent is immutable.
Merge pull request #96 from mispencer/CSharpProjectContentIsImmutable

CSharpProjectContent is immutable.
Add Semantic Errors method.
fixup! Add Semantic Errors method.
Better instantiating check
Implement crude Razor support
Rewrite file for client for Razor syntax error as well
Better creation of the razor host
Rewrite file for client for Razor samantic error as well