[c12511] Add support for VS2012 building.

[ci skip] for make travis happy ;)

(based on commit 3c73ecc)
(based on commit 6f97021)
(based on commit 3c9fca4)

In fact sync VS2012 support existed in repo to form similar other cmangos
repos. That also fixed some unexpected used VS2010 projects files in
VS2012 building.