Moved to raudio library repo: https://github.com/raysan5/raudio

Those functions were platform dependent and user has no control over the file created. They have been removed from raylib and just moved to `core_storage_values` example.

This example requires a complete remake to be more clear. Also current quaternion maths could have issues.

Disable color vertex attribute if not provided by mesh

Simplified example

REDESIGNED: `LoadDirectoryFiles()`
ADDED: `LoadDirectoryFilesEx()`
REDESIGNED: `LoadDroppedFiles()`
ADDED: `IsPathFile()`

This BIG BREAKING change simplifies the functions and gives more control to the user:
 - A new `struct FilePathList` has been added to avoid exposing complex pointers.
 - User is responsible of memory loading/unloading
 - Filepaths loading support recursive directories and file extension filters

RENAMED: `ClearDroppedFiles()` to `UnloadDroppedFiles()`

`physac` is available on its own repo

This feature is still under consideration/testing and it doesn't work properly, at least the Delay Effect processor.

WARNING: This addition is based on a PR and it's still under review, not sure if it will be maintained in the future. In general, raylib tries to avoid callbacks usage mechanisms.