When adding alpha mask to GRAYSCALE image, if using ImageFormat(), it could change pixel values, now we avoid that, mask is just added as an extra channel

While at it, add comment to indicate what the version signifies.

[a3f: updated commit message]

The result of `success` is actually never used. Either we should check
for it and return or remove it. I assume just checking the last one is
okay.

* Const corectness for LoadShaderCode

* Added const for standalone variant as well.

Contributed simple shader example

Still looking for a better way to integrate it into raylib API, maybe add a LoadImageAnim()?

Note that latest emsdk changed paths

Note this example is not working properly, it still requires some review.

- ADDED: CompressData()
 - ADDED: DecompressData()

This reverts commit 53b32f1c20.

Replaced DEPRECATED functions

...moved to internal AudioBuffer structure as totalFramesProcessed, now time measure works again... but there is some problem with looping...
Also note some inconsistencies between frames and samples, it seems those concepts are not considered correctly in the code.

I'm not sure why the clean command is so complex (especially given that find -type f -executable | xargs rm -fv works!)
but I fixed the version as is, to support x-pie-executable which was preventing it deleting anything on my system...