This reverts commit 4f6fbaed41.

Specifically, std.fs.OpenDirOptions struct no longer has the iterable
flag, now it's a standalone function call std.fs.openIterableDir

GetMusicTimePlayed() was calculated using buffered frames, not played frames.
For example: calling LoadMusicStream->UpdateMusicStream->GetMusicTimePlayed would return non-zero value, even though no music was playing.

Add R package raylibr as a new binding for the R language

Moved to own repo: https://github.com/raylib-extras/rmem

Tested with latest emscripten 3.1.18