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>

Tested on Raspberry Pi... Just note that platform is very limited by GPU...

* Removed Unused Uniforms

uniform vec3 viewUp;
uniform float deltaTime;

* Removed Unused uniforms

uniform vec3 viewUp;
uniform float deltaTime;

* Updated Source

  Added   - #define PLATFORM_DESKTOP line for desktop users.
            This now will correctly find the proper glsl version for the raymarching.fs file.
  Removed - Uniforms --> deltaTime and viewUp. Including the code that was setting them.
            They were never used and they were triggering a log warning.
  Removed - The const from both screenWidth and screenHeight.
            Now they can be used to update the shader resolution when screen is resized.
            NOTE : This is a quick fix and probably not the best idea.
  Added   - IsWindowResized() to check if screen is resized.
            If window is resized then width, height and shader resolution are updated.
  Changed - MIT tag at bottom right color value to BLACK. Now it's easier to see.

* Closer Match to original code

* Removed the PLATFORM_DESKTOP Define

Contributed simple shader example

* Update year of copyright notices

* Fix mistake in comment

* Fix typo ("algorythms")

* Replace tabs with spaces

* Remove trailing whitespace and fix mistake in comment

* Fix ExportImageAsCode missing comment rectangle corner

* Replace tab with spaces

* Replace tabs with spaces

Contributed by ProfJski

Now shader uses `fragTexCoord` that are the full screen texture coordinates normalized, instead of `gl_fragCoord`, the unnormalized screen coordinates

Also changed path to shader back to what it was originally.

Now dividing by the zoom instead of multiplying (in the shader), so zoom works as expected. Also zoom increase/decrease is now scaled depending on the current zoom.