* rlDrawMeshInstanced first attempt

* rlDrawMeshInstanced OpenGL 3.3 and VAO checks

* rlDrawMeshInstanced GetShaderAttribLocation; comments

* example instanced shader

* RLGL_STANDALONE RAYMATH_STANDALONE Vector4

* apply suggested naming changes; add instanced mesh example

* remove orphan variables

* updated README.md

* fixed CMakeLists.txt to allow building and debugging with Visual Studio Code and CMAKE Tools extension

* added PLATFORM_DRM
contains mouse pointer code from https://github.com/chriscamacho

* removed redundant cleanup in InitGraphicsDevice

* fixed DRM connector mode selection

* added choosen DRM connected mode to log output

* added respecting TargetFPS on DRM mode selection, default to 60

* added support for GetMonitorRefreshRate

* changed SUPPORT_MOUSE_CURSOR_RPI to SUPPORT_MOUSE_CURSOR_NATIVE

* changed avoidProgressive to allowInterlaced

* cleanup, function extraction and improved mode selection

* README reverted to original for PR

* line endings fixed for core.c

* removed old code

* mouse pointer reverted to small square

* replaced SetGraphicDeviceName() by DEFAULT_GRAPHIC_DEVICE_DRM

Co-authored-by: kernelkinetic <kernelkinetic@outlook.com>

This is the recommended way

Co-authored-by: codifies <nospam@antispam.com>

This reverts commit 2528854664.

* Update compilation warning flags

Removed the -Wall flag that allow many warnings and added manually all the warning flags that don't generate warnings in the src/external folder.
Specifically, these are some of the flags reporting errors in src/external:

-Wmissing-prototypes
-Wunused-variable
-Wunused-value
-Wunused-parameter
-Wunused-function

* Uptade compilation flags in examples with missing -std=c99

Co-authored-by: codifies <nospam@antispam.com>

Note that emscripten upstream branch implements the new asyncify implementation, expected to be faster than emterpreter one.

Now examples can be compiled by module, that's useful when compilation fails at some point

Actually OpenAL is not used any more, it should be using CoreAudio

Contributed simple shader example

I'm not sure why the clean command is so complex (especially given that find -type f -executable | xargs rm -fv works!)
but I fixed the version as is, to support x-pie-executable which was preventing it deleting anything on my system...

- Updated Makefile with new examples

* 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...

a minor issue: where the location of the file "raylib.rc.data" is wrong, and this will cause an error in compilation.

Contributed by ProfJski

Note that building examples for web as they are (no code adaptation for web avoiding while loop) implies using the emterpreter... and that's very slow!

Found some issues when building for web using latest emscripten 1.38.30, traced the error and found that eglGetProcAdress does not return function pointers for VAO functionality, supported by extension.

It requires more investigation but now it works (avoiding VAO usage)