[ENHANCEMENT] Implement shaders modding support

[DotWith]

Modifying shaders in runtime.
This would be widely expandable to modding custom levels, objects, etc. Other platforms that don't support shaders may need restrictions. The file extensions for shaders are as followed .frag and .vert.

[EliteMasterEric]

I investigated this at one point but never figured it out. It should be a matter of just opening a .frag and .vert yourself then loading it as a shader.

I did ask about it on the forums at one point and maybe the responses can help you.

https://community.openfl.org/t/how-to-load-gl-shaders-from-a-string/13298

[DotWith]

This modification of the openfl shader seems to get the job done.
https://github.com/gedehari/IzzyEngine/tree/master/source/openfl/display