add new muon variables to LoKi functors
They are the correlated chi2, and two BDTs
This is the same MR as !409 (merged) in master. To be cherry-picked in run2-patches
If people wants to use them in the stripping, this needs to be added as well as to 2017-patches for restripping. 2016-patches is not necessary as the variables were not included in the reconstruction.
Edited by Rosen Matev