* Use RL_QUADS/RL_TRIANGLES for single-pixel drawing

Addresses problem mentioned in
https://github.com/raysan5/raylib/issues/2744#issuecomment-1273568263
(in short: when drawing pixels using DrawPixel{,V} in camera mode,
upscaled pixel becomes a line instead of bigger pixel)

* [rtextures] Fixed scaling down in ImageTextEx

Closes #2755

* Added global audio processor

* Renamed struct member to follow naming conventions

* Added example for AttachAudioMixedProcessor