Fixed main menu button glitches, added achievements page that currently is...

Fixed main menu button glitches, added achievements page that currently is empty, added button for skins page and removed sounds as it will have a sound slider instead. Basic menus have been added for various pages on main menu to accomplish the various rewards and options. See commits for more detail. Note that the GUI for the powers seems not to be working in the previous dev3 and as such UIOverhaul as it is sourced from dev3, this should be fixed eventually in dev3.