Advanced Battery Box GUI

Quite a few changes to the Advanced Battery Box. 
1) When input/output is disabled or set to quantum, have it not show the relevant texture on the specified side
2) Made modes be an enum instead of just numbers 0 - 6
3) Made batteries and things charge/discharge when placed inside, regardless of mode
4) Fixed unlimited power bug where battery box wasn't fully disconnected from an attached network when changing mode/direction.
5) Made the boxes be able to be disabled (changing modes wasn't including off when cycling)
6)  Changed gui to be more intuitive (I think). Red X instead of blank square when disabled. Instead of buttons for direction changes, it's no a little graphic.
7) General refactoring of some things