Add some debug prints
Infer L3 tau producer location based on filter inputs

Needed for unscheduled/threaded HLT, where the producers are no longer
in the paths.
Use named constants instead of magic numbers
Unify helper directory naming in L1 and HLT plotters
Fix some efficiency plot axis titles
Use DQMGenericClient instead of HLTTauPostProcessor

In favor of a common tool. DQMGenericClient does everything
HLTTauPostProcessor does except the EfficiencyRefPrevious plot.
HLTTauPostProcessor will be modified to produce only that in following
commits.
Remove trailing '/' from the DQMBaseFolder configuration
Rewrite HLTTauPostProcessor to produce only EfficiencyRefPrevious plot

Everything else is now done with DQMGenericClient.

Remove HLTTauDQMSummaryPlotter as obsolete.
Merge pull request #3820 from makortel/tautriggerdqmTauProducer_DQMGenericClient

DQM -- Migrate Tau HLT DQM to DQMGenericClient+DQMEDHarvester