Replace Visual Studio with MinGW-w64 for Windows platforms

According to http://stackoverflow.com/questions/19425482/windows-c-compiler-with-full-c11-support-should-work-with-qt and my own experience, we should stop supporting Microsoft Visual Studio on this project for various reasons:
- Many C++11 features are not implemented (constexpr, noexcept,...)
- Some features have bugs that are not yet fixed (std::chrone::steady_clock)
- There are certainly other bugs not yet found

As a logical result, a code that is fully compliant with C++11 and builds perfectly with gcc must be modified, reimplemented or debugged to be compatible with Visual Studio.

The impact is that some coders have to make some additional work on the code to make it compatible, and this adds a delay to each PR that Visual Studio cannot build (currently 2 weeks on the component framework which is needed to step forward).

So:
- unless we consider that we have so many coders that we can make them work a a non-essential task,
- unless we have so much time to spill to make the code compatible with a non-free tool,
- unless we want spend 8 years on this project because we can't force Windows people to fix the code in time,

we should stop supporting the product to spend some time on the code of the game itself.