* core: added `GetMouseDelta()`

Thanks to previousPosition added by raysan it is now possible to create the GetMouseDelta() function.

Returns a Vector2 with the difference between the current and previous position of the mouse in a frame.

Useful for creating camera scrolling, among others.

* Added changes noted by raysan

Avoid possible symbol collisions

RENAMED: MeshBinormals() -> GenMeshBinormals()

- Improved command-line
 - Added XML support
 - Added sample outputs: DEFAULT, JSON, XML
 - Reviewed LoadFileText() bug
 - Removed trailing spaces

* Update BINDINGS.md

* Update BINDINGS.md

https://youtu.be/3dZenkpmRzM

Added missing null terminator when adding characters to the string, otherwise garbage values are read (often zeros which are equal to '\0', but not every time).

This error results in random characters appearing in the text box every one in a while:
```
asdfg??? ll??
```
It is corrected with the proposed fix.

This problem was observed by my student, Gonzalo Rivera Lazo.

Replaced: Returns -> Get

RENAMED: InitAudioStream() -> LoadAudioStream()
RENAMED: CloseAudioStream() -> UnloadAudioStream()

* review collisions ray-box and ray-sphere

* Applied raysan's refactor
Improved GetRayCollisionBox

* Replace GetRayCollisionGround with GetCollisionQuad

* Update example core_3d_picking

* Update example models_loading

* Fixed issues after merge

* remove debug stuff

Co-authored-by: Cry dsch <chris.obo@gmx.net>

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>