Updates in DT segments reco; bugfix in DT timing in MuonIdentification

-Bugfix in DT timing in RecoMuon/MuonIdentification

-Rearranged DT segment building code + updates to DT MT pattern reco. 
 (regression-tested: http://cmsdoc.cern.ch/~ptraczyk/plots_700.pdf)

-Validation/DTRecHits: moved histogram booking to BeginRun, as requested (https://github.com/cms-sw/cmssw/pull/1004#issuecomment-25805649)
 + updates to validation histograms and tools for plotting.