Script for controlling "mechanical" doors, aka custom doors using hinges.

Future features:
  * Rotor and piston support.
  * "Multi-stage doors", e.g. actuate a hinge, then a piston.

Currently this operates on hinges whose names start with "DoorX", where X is an arbitrary identifier.
Usage:
   Script argument should be a space-separated list of identifiers and either
   `-open` (default behavior) or `-close`.
   Failing to pass any identifiers will cause the action to happen to all doors on the grid.

By default "open" is assumed to be 90 degrees and "closed" is assumed to be 0 degrees.
   However, each hinge can have this behavior configured via custom data. A sample config
   (with the default values):

OpenAngle=90
ClosedAngle=0
Velocity=5

