Config Changer

Added an in-game config changer. It locates zipped configs stored in the assets folder, unzips them, and replaces the existing configs with them. I tried to add a way to restart Minecraft but that didn't work out due to the way the launcher vehemently disagrees with the whole idea. It's currently implemented via a GUI that displays after the mod download section does, but that can be disabled by commenting line 45 of UpdateGui.java