Delay in event processing

[gbaudic]

After the inclusion of the SDL2_gfx framerate manager, processing delays for keystrokes have become much larger. It is not uncommon to have to wait 5 seconds before the press on Escape (which triggers a quit event) effectively closes the window.
Removing the framerate delay in the main loop solves the problem.

[gbaudic]

The event processing was made using an if instead of a while. The issue is now solved as of commit 20bb7b2.