pressure plates tweak

Nodebox-based wall levers, take 2.
- This time it works -
Thanks, VanessaE

(though that means it's inconsistent with wall levers/buttons when placed
next to those, but it still looks good)

can actually rotate and activate nearby mesecons :-)   These look a little
better than the last try anyway.

added up/down pistons

microcontroller textures/nodeboxes