More locking updates. Introduced a new MultiLock to threadutil. This
lock will let a single thread acquire the same lock more than once,
keeping track of how many times this happens, and will release the
actual lock only when the lock's lock count gets back to zero. By
using MultiLock, various functions in Curses.py and Blinkenlights.py
no longer need to pass around to other functions a parameter
indicating whether or not a lock should be obtained. This was a large
cause of complexity and errors, which is now eliminated. Everything
seems to be working properly wrt locking at this point. The
Curses.Blinkenlights interface has achieved basic working
functionality.