[CGMZ] Preloader - Version Alpha R3

Hi all, today this plugin was updated to version AlphaR3!

This version adds some plugin commands to unload your image or audio files. Unloading fonts was not added as they are already quite small, so there is not likely to be any harm of leaving fonts loaded. Unloading images and audio can free up quite a bit of space, especially if you know those will not be needed in the future.

This is mostly adding the infrastructure for unloading preloaded images and audio, for a future update that will automatically handle the loading and unloading of these resources.

• Added plugin command to unload an image file
• Added plugin command to unload an audio file