* 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 ;-)

* Fixed an issue when using raygui and physac on unix systems
hash "#" is single-line comment character in bash so echo ignores #include and #define

* tab fix

We can figure out the source file location based on the location of the
build.zig file. No need to require the library user to specify where
raylib is stored.

* make const

* make const

* follow style guide

* Update rmodels.c

* Properly fix make clean under sh.exe

* Ensure make clean works properly under Windows if RAYLIB_RELEASE_PATH is modified

This reverts commit ab47c6401e.

Tested on the following environments:
 - w64devkit.exe
 - Windows 10 cmd
 - Notepad++ NppExec console

GNU make on Windows first tries to find sh.exe on the path,
and will execute build rules using it if it is present.
The make clean target uses the builtin cmd.exe command del, which
won't work under sh.exe

The reason this is not done for the entire Makefile is because it would
break cross-compilation of raylib.

- Adds a new OS clause to build.zig for the BSDs
- Tested on my FreeBSD box using https://github.com/Not-Nik/raylib-zig
- All demos build and render just fine.  Nice !