v3.120.1

This hotfix release fixes a number of minor issues with the v3.120.0
release, and also modularizes the included demo programs to cut down on
the number of compiled binaries.

Changes:
- hexadecimal strings in custom shaders may now include whitespace
- added 16-bit half float formats to the dummy pl_gpu
- significantly reduced verbosity of the included demo programs
- merged all of the demo program variants into a single binary that
  picks the best windowing system / graphical API at runtime
- install `plplay` when demos are enabled

Fixes and performance improvements:
- fixed an integer overflow in a texture bounds check
- fixed a false positive error in the test framework on 32-bit platforms
- fixed some minor issues with various outdated comments
- fixed a potential use-after-free in the `plplay` demo program when
  playing files containing embedded ICC profiles
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