Enable include reordering

[marcogmaia]

The purpose of this is for us to be able to do the following:

#include <raymath.h>
#include <rlgl.h>
#include <raylib.h>

Right now the only possibility is to include raylib.h first.

[marcogmaia]

@raysan5 I have one question:

Why don't we extract this repeating redefinition to a single source of truth? Something like internal/common_types.h?

[raysan5]

@marcogmaia Sorry but this change adds extra complexity to the header that I prefer to avoid.

Why don't we extract this repeating redefinition to a single source of truth? Something like internal/common_types.h?

I prefer to keep the raylib.h header self-contained and not-dependant on other headers.