Trying to define a global transformation matrix to scale all content for HiDPI.

Probably required for HiDPI support

Found some issues when building for web using latest emscripten 1.38.30, traced the error and found that eglGetProcAdress does not return function pointers for VAO functionality, supported by extension.

It requires more investigation but now it works (avoiding VAO usage)

Users can define their custom memory management macros.

NOTE: Most external libraries support custom macros in the same way, raylib should redefine those macros to raylib ones, to unify custom memory loading. That redefinition is only implemented as example for stb_image.h in [textures] module.

At least until a proper solution is found!

This needs to be tested on a hi-DPI monitor, probably requiring a FLAG to enable it would be a good idea...

Based on pull request from user "DarkElvenAngel", better integrated with the current event system and enhanced with buffer to help with fast typing at low framerates.

Now core does not depend on textures module directly, only through text module.

Removed possible memory leak when using this function

It was not working on Windows 10

...while using a RenderTexture combined with 3d mode

clang was complaining about the type conversions. For example...
```
node_modules/raylib-src/src/core.c:1888:15: error: cannot initialize a variable of type 'char *' with an
      rvalue of type 'void *'
        char *cmd = calloc(strlen(url) + 10, sizeof(char));
              ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Function provisional renaming... that's not the end of this issue...

Following raylib notation rules

This reverts commit 1fe6d9fc06.

Because upstream GLFW now contains a fix.

Same functionality could be achieved using FLAGS... but also considering removing raylib logo animation...

Decided to allow user to provide values directly instead of requiring a Vector2 struct, probably more confortable to use.

 - SetMousePosition()
 - SetMouseOffset()
 - SetMouseScale()

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

- Didn't set X and Y values correctly.

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

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.