Rename projects, assemblies, and preprocessor directives to more closely match NuGet packaging
Use the client profile for the .NET 3.5 and .NET 4.0 builds
Rename Sharpen namespace to Antlr4.Runtime.Sharpen to avoid naming conflicts
Merge pull request #54 from sharwell/sharpen-namespace

Rename Sharpen namespace to Antlr4.Runtime.Sharpen to avoid conflicts
Merge pull request #55 from sharwell/client-profile

Client profile