Support custom allocators

This could be required on texture packing ;)

Short non-looping sounds can sometimes think they need to keep playing and will output their first few frames again. This helps to break out of all the loops instead of just this one.

* Normal vbo not correctly updated

* We get the video mode from the target monitor and use that to set, therefore
keeping windowed-fullscreen
* Added a GLFW_AUTO_ICONIFY 0 hint so that glfw does not minimize the window
when changing focus from a windowed fullscreen window. This is more expected
behavior for windowed full screen, when a user alt-tabs or clicks on a window in
the other monitor, they expect their windowed-fullscreen window to remaining up.

We were doing this before, but it was deleted during the
last GLFW update. Readd it to fix the associated macOS CI failure.

Fixes: ea5cd42e6 ("Update GLFW to version 3.4")

If press/release events for a mouse button come too fast, then using
`IsMouseButtonReleased()` does not work. This has been noticed when
using a touchpad on Linux when tapping with two fingers two emulate
right mouse button click.

The situation looks like this:

```
BeginDrawing           <-- current==released, previous==released
Pressed                <-- current=pressed
Released               <-- current=released
IsMouseButtonReleased  <-- returns false because current==previous
EndDrawing             <-- previous=released
```

The fix is to update the previous mouse button state in addition to
current mouse button state when `MouseButtonCallback()` is called by
glfw. Now the situation is as follows:

```
BeginDrawing           <-- current==released, previous==released
Pressed                <-- current=pressed, previous=released
Released               <-- current=released, previous=pressed
IsMouseButtonReleased  <-- returns true because current!=previous
EndDrawing             <-- previous=released
```

It seems to work ok on my old Intel HD Graphics card... it should work anywhere else

* fixes for switching full-screen and v-sync

* requireVsync flag

- Renamed GetGlyphIndex() parameter
 - Review DrawTextEx() implementation
 - Review DrawTextRecEx() implementation

* swapped comments, expanded comment for clarity

* revert alignments

* adjusted for consistency

Just simplified code a bit