Still trying to track down deadlock bug for preemption.  Realized that uuids are actually priorities, not timestamps and had older/younger check backwards.
In performing gte checks, had confused age with priority.  Now, consistently, if one side has a larger uuid, then it has priority.
In try_next, can cause events to backout.  If we do cause other events
to backout, then backout calls try_next.  This (in some cases) can
invalidate state that we're already dealing with in the parent
try_next.  Use this flag to keep track of whether already in try next.
If are, then return out immediately from future try_next calls.
Forgot to unlock after backing out.
When attempt to perform additional operations after backout, should get an exception.  Otherwise, fail.
Added code for forwarding backout request from root node.  Mostly untested.
Root event now sends messages out as part of its finishing its
individual first phase lock.
Refactored locked test util code to use Waldo Endpoint class.
Incomplete test file for testing that endpoint calls are handled correctly.
Reworked endpoint call tests so that have each endpoint is capable of receiving an endpoint call to a function that reads the internal variable's value and returns it.
Refactored code in waldoLockedActiveEvent to make file more readable: moved event parents into their own file.
Each active event must keep track of other endpoints that it called.  This is done using an EventSubscribedTo object from waldoEventSubscribedTo.py.  Pretty much just a copy-paste of an activeEvent's SubscribedToElement.
Added mechanism to make endpoint calls using new locked objects and
added test code to strain it.  Currently, the test produces an error:
still need to transition context logic over to creating a locked event
object instead of a traditional, commit-time validated, event.
Transitioned active event map to use new locked objects.
Minor code cleanup + added a method to locked events to check status
of peered variables during commit.  That method is just a placeholder
for now.
Using threadsafe queues to signal when an event completes.  Additionally, moved logic for first phase of commit in event parent into root object because actions are common between all subclasses.