2017-10-25 Rec v19r6

This version uses Lbcom v18r5, LHCb v40r5, Gaudi v27r1 and LCG_84 with ROOT 6.06.02.

This version is released on `2016-patches` branch.

Change to release notes format

On this branch, the file LHCbSys/doc/release.notes is frozen
Instead, there will be a file per release in the new ReleaseNotes directory. e.g. this file is called ReleaseNotes/v19r6.md

Bug fixes

[MR !752] Update State provider key to be based only on memory address
[MR !773] Fix to VeloMuonBuilder distance cut