Added insert/remove capabilities to MemoryExperiment.
Updated WCInput to not save chunks if checking is turned off.
Fixed memory leak by having Mods store their own value, so that its
automatically garbage collected.
Fixed a bug with the last commit where nontbd wasn't being run correctly.
Changed Node to only record its stacktrace if debug is on, for memory reasons.
Added MemoryExperiment to mkexamples.
Fixed a bug where memo entries were being removed from the table when matched,
preventing another match in the next round.
Fixed the Partitioned modifiers to spread inserts out equally over the
partitions.
Merge branch 'master' of https://github.com/twmarshall/tbd
Added removal of empty signatures to DDG.cleanup to prevent the memoTable from
growing unbounded.
Removed unnecessary Task object from Worker.
Turned ModId into a 'type' to save memory.
Fixed memo to not match nodes that come before already matched nodes under
the currently reexecuting read, since the timestamps would be out of order.
Experiment can now change the timeout in Constants, so that I don't have to keep
manually changing it back and forth.
Modified DoubleModList to prevent any calls to the mapping function when a
remove happens.