Merge branch 'v42r6-release' into 'master'

Documentation and dependencies redone for the v42r6 release after an important update.

See merge request !94

ReleaseNotes/v42r6.md

-2017-08-29 DaVinci v42r6
+2017-08-30 DaVinci v42r6
 ========================
 
 Release for 2017 production
@@ -9,8 +9,7 @@ It is based on Gaudi v28r2, LHCb v42r6, Rec v21r6, Phys v23r6, Analysis v18r5 an
 Uses LCG_88 with ROOT 6.08.06.
 
 - Numerous nightly tests and test references updated.
- DaVinciTests/tests/qmtest/commonparticles.qms/test_standardintermediate_reco14_run.qmt
-    Updated test reference file merge-small-files.ref.
+  - See e.g. merge request !93
 - Place Moore RecSummary in a stream-dependent location.
   - See merge request !79
 - Handle missing Hlt2 SelReports in Tesla.