Required to attach multiple color textures and multiple cubemap faces

* fixed wrong error message for input device

* error message without errnofor input device on RPI
 to prevent from including additional header

Co-authored-by: kkl <klingenberger@bfmc.de>

This redesign allows more flexibility when creating RenderTexture and a simplification (and hopefully removal) of `GenTexture*()` functions, that should not belong to this model but the user code, due to the use of custom shaders.

Also, this new API opens the door for a possible GBuffers type and advance rendering possibilities...

Some functions of the API have been also simplified or even removed.

rlgl module can be used as an standalone library, so, a version for the library has been added: v3.1.0, matching current raylib version.

Not required anymore, attachment type is queried when required

Avoid unloading default shader, raylib will take care of it

Before deleting certain objects, they must be detached from their parents. That's the case for shader objects after linkage to shader program and also for the texture/cubemaps/renderbuffers attached to framebuffers. If objects are deleted before detached, they are kept in memory to avoid accessing deleted data.

Better organized and commented

Also updated raylib Wiki about struct sizes in 32bit and 64bit

Replaced Vector3 by direct values, easier to use and understand

Co-authored-by: Ray <raysan5@gmail.com>

- raylib-cpp
- raylib-lua-sol
- node-raylib
- raylib-js
- raylib-chaiscript
- raylib-squirrel

Co-authored-by: Ray <raysan5@gmail.com>

rlBlendMode() has been added to rlgl to be used on BLEND_CUSTOM. This functionality is exposed to advance users.

In any case, new blending modes could be added if required.

Co-authored-by: max <max.cedercreutz@cetopo.com>