title: Visual Studio 2015 appears to complie VB code with C#
body: <pre>
  Steps to Reproduce:
  Create new Visual Basic Analyzer with Code Fix (NuGet + VSIX)
  From VSIX project add New Item...
  Extensibility/Custom Command called "CustomCommand"
  Not required but helps see the issue set the following options
      Option Explicit Off
      Option Strict Off
      Option Infer On
  Build Solution
  </pre>
  
  <p>Several files are added and you get 381 warnings for the ComandComand.vb and CustomCommandPackage.vb files. The warnings are "Type or namespace definition or end-of-line expected", "Newline in Comment", "Type Expected" , "Too many characters in character literal"., "Comma Expected". None of which make any sense in a VB file. If I included these files in a C# project and rename them to .cs I get the exact same errors. The errors make no sense for a .VB file. </p>