Fixed welding down machines.

Added the state var to all machines. 0 is unanchored, 1 is anchored, 2 is welded.
Added the WELD_FIXED flag for machines that can be welded down.
Added the weldToFloor proc, which is used to toggle welding down for machines.
Fixed machines not using general procs.
Fixed some relative pathing.
Merge pull request #1889 from ComicIronic/WrenchWeld

Fixed welding down machines.