Loading of last level implemented in revision 93ffabe619cf
Loading of player class implemented in revision 69a0b5d7fcda
Currently it loads the last map automatically, but I'll add "new game"/"continue" buttons.
There's no way I can think of to implement skipping back to a previous level at this point due to the way the levels are loaded. We should be able to fake it by using copies of the level without enemies.