Patch hierarchyconstraints to CMSSW_7_1_X

This patch has been prepared by Gero Flucke some time ago, see https://twiki.cern.ch/twiki/bin/viewauth/CMS/TkAlignmentLegacyThoughts, first topic. Testing happened on CMSSW_4_4_5. Results were presented in the alignment meeting of Oct 31, 2013, where the modifications got blessed. See https://twiki.cern.ch/twiki/bin/viewauth/CMS/TkAlPullReq201401 for more details and link to the presentation.
This is an outstanding issue since months that was not put into git.