Add more information about C++ exceptions

[n0F4x]

I am struggling to find out the kind of exceptions each function can throw if any. (Maybe I am just a noobie, so excuse me for that.) I would like to raise this issue to write documentation about the exception policy of the library, which right now, it lacks. And also, to mark functions that do not throw with noexcept.

[charles-lunarg]

This library doesn't throw any exceptions of its own, but does use standard library types (std::vector, std::string) which are liable to throw.

I could mark stuff as noexcept, and probably be fine but I'm not sure adding noexcept adds much. I'm not too worried about performance since this is an initialization library rather than runtime.

I certainly could add this disclaimer to the readme or other documentation.