Simplified some parts and reviewed for a correct computation of matrices, considering stereo render view/projection per eye transformations

shaders_rlgl_mesh_instanced -> shaders_mesh_instancing

* Fix some warnings in examples.

* cleanups from review

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

- Some rlgl functions have been moved to core
 - Some functions have been made internal to rlgl
 - rlgl functions prefixed with rl*()

Some enums values have been renamed to be more consistent and also provide a more detailed description:
 - ShaderLocationIndex:    LOC_VERTEX_POSITION -> SHADER_SHADER_LOC_VERTEX_POSITION
 - ShaderUniformDataType:  UNIFORM_VEC2 -> SHADER_UNIFORM_VEC2
 - MaterialMapType: MAP_ALBEDO -> MATERIAL_MAP_ALBEDO
 - PixelFormat: UNCOMPRESSED_GRAYSCALE -> PIXELFORMAT_UNCOMPRESSED_GRAYSCALE

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

New implementation allow enabling additional textures per batch only.

Reduce size and better license CC0

* 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

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

This function was renamed for consistency in raylib 3.0, just unified all examples to use TextFormat() instead of FormatText()

* Make raymath naming and functions more consistent

* Minor fixes

* Fix examples

* Fix Physac

* New naming rules

* Apply naming to Quaternion functions

* Apply to models.c

* Remove *MulitplyValue / *DivideValue

NB glsl100 shader needs testing on "bare metal"

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

It seems something is not working properly...

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

head can't think of any improvement I could use on the shaders for
version 120
This has been tested on Linux (Desktop) requires testing on a Rpi

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