NOTE: Two libraries still use custom allocators: glfw and stb_vorbis

Use new file I/O ABI

There could be some cases where we need to define the internal audio buffer size, now it's possible.

RENAMED: InitAudioBuffer() to LoadAudioBuffer()
RENAMED: CloseAudioBuffer() to UnloadAudioBuffer()

Renamed some defines and reviewed some comments.

Just for clarification, no plans to remove libc dependency, just did some code analysis to see how much raylib depend on stardard C library. My conclusions:

 - stdlib.h: primary dependency is for malloc() and free()
 - stdio.h: primary dependency is for FILE access, maybe it could go through a custom ABI?
 - string.h: just around 8 functions required
 - math.h: just around 8 functions required
 - others: 1-2 functions required for some other headers

* Update to miniaudio 0.10

This replaces the old ma_pcm_converter with ma_data_converter.

At this time of this commit, miniaudio 0.10 is still in the testing
phase. To make it easier to update miniaudio.h during this period, I've
temporarily moved the @raysan5 Win32 customizations to raudio.c because
there may be quite a few updates to miniaudio.h during this time.

* Use miniaudio's built-in volume control.

Added SUPPORT_TRACELOG_DEBUG config

* [core] REDESIGNED: Implement global context

* [rlgl] REDESIGNED: Implement global context

* Reviewed globals for Android

* Review Android globals usage

* Update Android globals

* Bump raylib version to 3.0 !!!

* [raudio] REDESIGNED: Implement global context

* [raudio] Reorder functions

* [core] Tweaks on descriptions

* Issues with SUPPORT_MOUSE_GESTURES

* [camera] Use global context

* REDESIGN: Move shapes drawing texture/rec to RLGL context

* Review some issues on standalone mode

* Update to use global context

* [GAME] Upload RE-PAIR game from GGJ2020 -WIP-

* Update game: RE-PAIR

* [utils] TRACELOG macros proposal

* Update config.h

Short non-looping sounds can sometimes think they need to keep playing and will output their first few frames again. This helps to break out of all the loops instead of just this one.

* explained a bit more the core_window_letterbox example

* fixed a few 'ups' moments that could lead to mild head pain and time loss

The result of `success` is actually never used. Either we should check
for it and return or remove it. I assume just checking the last one is
okay.

Replaced DEPRECATED functions

...moved to internal AudioBuffer structure as totalFramesProcessed, now time measure works again... but there is some problem with looping...
Also note some inconsistencies between frames and samples, it seems those concepts are not considered correctly in the code.

All data should be properly initialized by now

Renamed for consistency with similar functions

Now, multiple music parameters are exposed to the user!

This module has been completely reviewed, old structures still contained OpenAL useless data, a full module revision. Some of the changes:
 - Redesigned internal MusicData structure
 - Exposed MusicStream structure data
 - Reviewed AudioStream structure
 - Redesigned Sound structure

Still some work to do...

- Capital letters at beginning
- for loop spacing and brackets
- Functions naming for consistency
- Example following examples template
- Other tweaks

* added multi channel sound replay to raudio
added -fPIC to Makefile for Linux
added simple lighting and audio multi channel to examples Makefile

* not properly reporting audio buffer pool size...

Users can define their custom memory management macros.

NOTE: Most external libraries support custom macros in the same way, raylib should redefine those macros to raylib ones, to unify custom memory loading. That redefinition is only implemented as example for stb_image.h in [textures] module.