Now at a point where can issue run and hold requests, receive their
return values, and initiate the committing of the chain of run and
holds that the endpoint made.  Still need to actually receive and
process the commit and work out backout scheme.
Added received commit code for run and holds.
Added code for emitting default value of endpoint type.  Not really a
good value to use instead of endpoint type, so just used None for now
and printed a warning message.
Function calls on endpoint objects now treat the endpoint itself as
something that got written to in slicer.py.
Forwards reservation request result messages along run and hold chain (still not forwarding over network yet though, nor dealing with revoke and retry).
Minor typos fixed in reservation manager and revoke.
Had a bug where was not handling re-entrantness of run and holds properly.  Fixes handle re-entrantness correctly, but now have a bug where am improperly copying over values in contexts.  Importantly, may want to re-use contexts rather than create new ones and copy them over.  Resolve tomorrow.