Release of Gauss v55r3 for Sim10

This release will be based on Gauss v55r2 and introduce new functionality as well as pick up pending technical changes that will ease maintenance and ease the transition to Gauss-on-Gaussino

It is based on Gaudi v36r0 and LHCb v55r1 and LCG_100 but it uses a new LHCB_7 layer.

It includes the first beta release of the Lamarr ultra-fast simulation:

• MR !513 (merged) (initial deployment) and !780 (merged) (based on sciKinC for Run12)

It also include changes to MadGraph to a new version for longer term production support:

• MR !771 (merged) (new versions of MadGraph 2.9.3) and !777 (merged) & !787 (merged) (fix issues with LHAPDF paths)