Fixing the mutex locks/unlocks; can close a door after it's opened.
CAN INTERRUPT DOOR OPERATIONS NOW (CLOSED -> OPENING -> STOPPED -> CLOSING, USING 3 'r' INPUTS). NEED TO FIGURE OUT TIMER LATER (I HAVE AN IDEA). Added semaphore for granting permits to process commands. Removed extra mutex locks/unlocks. Put debug information inside if-defs (currently turned off).