The vanilla main menu is an awful pile of code that is extremely painful
to make additions to. So I've side-stepped the problem by writing an
entiely new menu system without all of vanilla's quirks. I've separated
the custom menu system from the menus I want to make, which allows for
easy additions and a clear separation of responsibilities.
Along with this rewrite comes a host menu, adding the missing
configuration options in-game.
Fixes#29
