GUI texture atlas is misleadingly named

The name for the texture atlas is just "gui", but rather than containing full GUIs, it only contains GUI sprites. It is expected that the name would more accurately reflect what is included in the atlas (such as "gui_sprites").

A very similar atlas, the atlas for map decorations, is properly called "map_decorations" (and only contains the decorations, and not the map background textures). So it is an inconsistency as well.