Fix what appears to be a major bug in the way the presence of an ECAL shower was determined for a particle based on the ReducedEvent.
Try to implement cuts aimed at reducing the bump in the TRD proton likelihood distribution.
Adjust lower cuts on charges.
Simplification.
Create TrdHits from TrdTracks.
Remove code duplication.
Store minimum pdf value in Settings.
Move generation of toy-MC dE/dx values from TrdQt to TrdPdfLookup, in an effort to make this
functionality easier accessible. In particular, this is needed for toy-MC generation based on
TRD tracks.

Add convenience functions to TrdPdfLookup that take Xenon pressure and rigidity directly instead
of bin numbers.

Include a test script for toy-MC generation.
Merge remote-tracking branch 'origin/dev' into trd_tracking

Conflicts:
	interface/TrdQt.C
Trivial changes.
Fill histograms to study proton rejection based on TRD tracking.
Merge remote-tracking branch 'origin/dev' into proton_bump

Conflicts:
	cuts/ECALCuts.hh
Use generalized 3D->2D projection everywhere.
Adapt TRD track selection cuts and include particle spectrum after TRD track selection.
Merge remote-tracking branch 'origin/proton_bump' into trd_tracking

Conflicts:
	programs/trd_calibration/test_trd_proton_likelihood_selection/test_trd_proton_likelihood_selection.C
Merge remote-tracking branch 'origin/dev' into trd_tracking
Remove obsolete FIXME.
Unify all calculations of TRD likelihoods in the new TrdLikelihoodCalculator.

There are a number of subtle issues that have to be taken care of in the calculation
of TRD likelihoods, see the documentation of the new class for details. Using the
new calculator everywhere ensures that likelihoods are calculated in exactly the same way
across the software, and that subtle effects are taken into account properly.
Fill toy-MC histograms for likelihoods based on TRD tracking.
Study different strategies for dealing with underflow hits.
Implement rigidity scan for electron likelihoods, in order to extend
the rigidity range of the rejection calculation (Professor Schael).
Code cleanup.