Digital valves can now be made and unwrenched. Fixes pipe fitting names.

You can now dispense digital valves from the pipe dispenser and wrench them in place and stuff. Should be useful for when you want a valve that the AI can control.

Also removes mentions of "unary vent" and replaces them with "vent" because Unary Vent is pretty confusing when it's always called "vent" or "vent pump" elsewhere.

Same goes for "mvalve".

Only the things displayed to players are displayed, there are no changes to how they're called in the code.