Added SetMouseOffset

- SetMouseScale changed to take in a Vector2.
- Added mouseOffset global which is used in mouse read functions.

utils: declare funopen only on Android

- Didn't set X and Y values correctly.

- Changed mouseScale to Vector2.
- Added SetMouseOffset to change XY of mouseScale.

funopen is only needed on Android, so declare it
only there. This fixes following MinGW build failure:

utils.c:50:7: error: conflicting types for ‘funopen’
 FILE *funopen(const void *cookie, int (*readfn)(void *, char *, int),
       ^~~~~~~
In file included from utils.c:45:0:
/usr/include/stdio.h:586:7: note: previous declaration of ‘funopen’ was here
 FILE *funopen (const void *__cookie,
       ^~~~~~~

Useful for tiling and offset parameters definition.

Added a bunch of useful text management functions.
Consequently, some already available functions like `FormatText()` and `SubText()` has been renamed for consistency. Created temporal fallbacks for old names.
raylib version bumped to 2.3.

Problem aligning provided vertex data to multiples of four, because main buffer is intended to bu used with indexed quads... but also shared with triangles and lines.

Despite issue is corrected, now module loop doesn't work...

Changed parameters order for consistency with LoadFontData() and other functions when an array is passed by parameter and array size is the following parameter.

OpenGL extensions loading could be improved...

Also reviewed rlCheckBufferLimit()

Now rectangle coordinates refer to upper-left corner instead of bottom-left

Now it should work... but this behaviour could be driver dependant...

Useful in case raylib compilation want to be automated and compilation config flags provided by command line.

It's broken.

To generate 2D polygonal shape

To draw only in defined area of the screen
ADDED: BeginScissorMode(), EndScissorMode()

- Reorganized some variables: Not used on OpenGL 1.1
- Now mipmaps can be generated on OpenGL 1.1 backend
- Renamed whiteTexture to defaultTextureId