Added comments for the future

From the Clang documentation[1]:
> -x<language>, --language <arg>, --language=<arg>
> Treat subsequent input files as having type <language>

Follow the advice. Fixes #840.
[1]: https://clang.llvm.org/docs/ClangCommandLineReference.html

This reverts #841 commit 97160fd970.

Note that all meshes are loaded as a single one at this moment, loading should be improved!

This reverts commit 4773de26a5.

which adds -lwinmm at the wrong place. It should be in the raylib
linker flags, not GLFW's.

Fixes: e0e2346c22 ("NO SUPPORT_BUSY_WAIT_LOOP by default")

Now it's required on Windows if not using a busy wait loop

Square root calls are computationally expensive.  In this case, they can be avoided.  Instead of checking distance<RadA+RadB, check distance squared against (RadA+RadB) squared.  The dot product of Vector3Subtract(B,A) with itself gives distance squared, so I used this code instead of an element-by-element computation of distance squared.  The only downside is that your geometric code is very readable, whereas this is less so.

Required for high resolution timer

Some minor tweaks

Variable operations inside the functions should be evaluated before the function operations.

This fixes the current CI failure.

We were doing this before, but it was deleted during the
last GLFW update. Readd it to fix the associated macOS CI failure.

Fixes: cd934c9f6 ("Update GLFW to 3.3.1")

Added guards to not redefine it if the user is using it with raylib.h
also added an 'f' at the end of the define to keep compliant with raylib's PI define

PI is not always defined in math.h, thus it must be defined in this header

Not sure if already corrected...

This change could break things. So, I created SUPPORT_HIGH_DPI flag to enable it (disabled by default).

Basically, it detects HighDPI display and scales all drawing (and mouse input) appropiately to match the equivalent "standardDPI" screen size on highDPI. It uses screenScaling matrix to do that.

This scaling comes with some undesired effects, like aliasing on default font text (keep in mind that font is pixel-perfect, not intended for any non-rounded scale factor).

The only solution for this aliasing would be some AA postpro filter or implementing the highDPI scaling in a different way: rendering to a texture and scaling it with FILTER_BILINEAR, check `core_window_scale_letterbox.c` example for reference.

Use at your own risk.

Some tweaks on BeginVrDrawing()