Big overhaul, click more for changes:
Added functional buttons to GUI.c, check demo for test usage
Added more options to debug (background)
Fixed some image drawing bugs (scaling)
Added subimage (Any Image struct can be a subimage, use image_subimage to grab)
Added gridsplit (new type ImageGrid can be set using image_gridsplit which will split an image into rows and columns)
Added strlens (get strlen but for text_draw)
More changes I probably forgot