Feature/msvc discovery
Feature/msvc discovery

It's finished !! Now, it fully support MSVC from 9.0 to 14.0, and all theses standalone distributions:
- Microsoft Visual C++ Compiler for Python 2.7 (MSVC++9.0, x86, amd64)
- Microsoft Windows SDK 6.1 (MSVC++9.0, x86, x64, ia64)
- Microsoft Windows SDK 7.0 (MSVC++9.0, x86, x64, ia64)
- Microsoft Windows SDK 7.1 (MSVC++10.0, x86, x64, ia64)
- Microsoft Visual C++ Build Tools 2015 (MSVC++14.0, x86, x64, arm)

Next step:
- Code review.
- Test it with some MSVC versions/Architectures/Python versions combinations.

I have also some comments on the global implementation:
- I think `msvc9_find_vcvarsall` can now be deleted.
- Maybe rename the file, by example "msvc_support.py".
- Maybe Implementing it (And other distutils patchs) for not be only called by "setuptools", but also by "pkg_resources": This will automatically activate patchs for some externals packages like "Cython" transparently.
pypa/setuptools,pypa/setuptools,pypa/setuptools