Place up/down pistons automatically depending on the player look direction, remove the craft recipes for up/down pistons, and unify all the pushing/pulling behaviors into mesecon:piston_push(pos) and mesecon:piston_pull(pos).

Conflicts:
	mesecons/internal.lua

Port a lot more (basically everything apart from gates, pistons and extrawire crossing) to the new nodedef system. There are some problems with wall button and wall lever (in the way they visually connect to wires)

Finish new mesecon-in-nodedef for conductors and receptors. Make wires and switch use it for reference.

New branch: Move mesecon to node definition instead of functions like register_conductor; first steps: move everything to legacy

Speed update of pressureplates up by using node_timers

Fix a bug (in some cases the output rules of a receptor weren't respected, bug introduced by commit before, 64d109b3)

`mesecon:updatenode()` was written to work only with conductors, though in several places it was used on recepters and effectors. This issue, reported by simion314, is fixed in this commit by explicitly checking for the type of mesecon node being updated.