initial seesaw proposal
implemented seesaw locking model. Tested. Only flaw: simultaneous locking
removed sysouts
Publish the result of the lock request to the callback.
Code clean up.
Unlock shouldn't need the seesaw barcode as argument.
Cannot request lock when already holding a lock on a different seesaw.
Fix error messages.
Remove request before acquiring a seesaw lock.
Remove unused seesaw request constant.
Merge pull request #9 from tgoossens/wip

Communicate about locking and unlocking of seesaws.