up/down pistons from certain directions

Thanks to HybridDog for spotting that

Fix bugs in the Luacontroller (when placing, false input pin values were given) and fix variables
leaking into the global environment in pistons.

Settings can now be retrieved by mesecon.setting(<name>, <default>) and can be modified without
editing the source code by adding the setting to minetest.conf
For instance, you can add mesecon.blinky_plant_interval = 0.5 to minetest.conf in order to
increase the blinking speed.
Rewrite the blinky plant with nodetimers.
Fixes #161

flexibility and because it was never inteded to be OOP in the first
place.

mesecon.receptor_on and mesecon.receptor_off are provided by wrappers
(mesecon:receptor_on/off) for compatibility, but will be removed. Mod
programmers that use mesecons: Please update!

Also, fix microcontroller polluting the global namespace and remove some
deprecated stuff.

Just some minor issues like dead code.

Up/down pistons should also have special rules excluding the pusher side (rotated versions of normal pistons).

Support metadata in piston pushing (so that microcontrollers and such can be pushed), support pushing chests (not locked ones though), and add two missing rules for pistons (z- top and bottom, but not z- itself). This still avoids the piston pushing power source issue.

Digging and footstep sounds for everything that needs them! Plus, pushing buttons, punching switches, and flipping levers all make sounds.

equivalents

Make load times faster by avoiding inventorycube and wielditem creation in technical blocks such as active wires and various piston orientations.