Events waiting can be enabled/disabled, it toggles event polling.

* Add support for truncating parser input

* Remove RLAPI from implementations in rlgl.h

This immediately shows log messages when stdout is not connected to a
tty.

Remove line that caused a memory leak

Avoid calling `abort()`, `LOG_ERROR` already manages it. Code looks cleaner now.

* Augment raymath.h with useful functions

* Rename Vector2ClampMagnitude and Vector3ClampMagnitude to Vector2ClampValue and Vector3ClampValue

* Remove Vector3{Up,Down,Left,Right,Forward,Backward}

When referring to byte array SIZE, I find it more clear than length

This feature is still under consideration/testing and it doesn't work properly, at least the Delay Effect processor.

WARNING: This addition is based on a PR and it's still under review, not sure if it will be maintained in the future. In general, raylib tries to avoid callbacks usage mechanisms.

This is a tiny change that makes code in src/rtextures.c "fold"
correctly in editors/IDE's by matching the number of opening
parenthesis to closing parenthesis.  One of those editors is Emacs ;-)