VS2010 MSBuild for c++ project

1. On VS2010, VC project builds with MSBuild (vcxproj) to get a consistent building system for all languages.
2. No matter which platformtoolset is selected (v100 or v90), MSBuild is used for building vc project.
3. Multi-targeting
--C++ Native Multi-Targeting: change PlatformToolSet between v100 and v90.
--C++ Managed Multi-Targeting: Add / configure TargetFrameworkVersion manually in vcxproj file.
--C# Multi-targeting: change "Target Framework" directly in project property.

Refer to:
C++ Native Multi-Targeting
C++ Managed Multi-Targeting
C# Multi-targeting