Added the start of the change prop algorithm
Change propagation works in situations where the ddg doesn't change as a result of reexecution, and timestamps are generated.
Cleaned up the management script and added another example
fixed some bugs with the testing framework
Added subddg generation
Change propagation now deletes the appropriate things and regenerates the ddg from memoized subddgs
Merge branch 'master' of https://github.com/twm378/incremental
Added support for adapting timestamps when using memoized subddgs
Added testing framework