Suggestion: Better control for power grids

Add a power splitter block which allows you to control how much energy goes to each side, for uneven power splits. Extra: add analogue redstone control for it (so power 3 means 3/15 goes to left while 12/15 goes right, power 0 means all goes right, power 11 means 11/15 to left and 4/15 to right etc.)