added support for ninja generator

[RisingLiberty]

I added a generator to create Ninja files, and Ninja projects and solution, making it easy to build everything

[RisingLiberty]

I'm still developing this as I'd like to clean up the code while also fully support MSVC, Clang and GCC.
The compiler's standard library is not found when using the Ninja files (CMAKE has the same problem)

[RisingLiberty]

support for gcc is added, support for static libraries and dynamic libraries (except dynamic libs for gcc) and dependency support as well.
I will use it now in practice, but my initial tests were successful

[RisingLiberty]

Verified on a bigger project of mine that combines static library, executable and unit tests. All were successful

[jspelletier]

Hi,

Sorry for the lack of comments for your PR. We are in major repo ownership changes. We will take a look at your changes eventually.

Thanks for your understanding.