Add code to write out a skim of accepted (positive track) events.
Print out the hit cross talk flag in operator<<().
Always sort hits by (cell,time) when printing out.
Implement printouts for TimeWindow and TimeWindowingResults
A more robust DC time windowing code.

Until now a stray hit could screw up the "stream" of a time window
and affect assignment of other hits.  The fix makes windowing result
independent of the order in which the hits are seen.
Simplify hit preprocessing interface.

There is no need for internal buffers because hits by value
are held by the EventClass, and we treat them as const.
TDCHitPreprocessing: change interface to use the same data class for filter input and output.
Fix a newly introduced bug
An option to apply MOFIA XTalk removal in addition to Clark filtering.