AlgContext keeps a reference to EventContext to use it in the destructor.

Passing a temporary will lead to undefined behaviour.

See merge request gaudi/Gaudi!838

Update clang format to 8

See merge request gaudi/Gaudi!872

and into a dedicate FixTESPath mix-in. GaudiCommon uses
this mix-in to remain backwards compatible.

This will make it possible to migrate away from GaudiAlgorithm and
GaudiTool, while keeping the TES path manipulation utilities available

moved the code into ApplicationMgr and control it via options

still use the old way for a few special cases or if GAUDIRUN_USE_OLDINIT
is set

Specializations of Gaudi::Application can be used to override the main
application logic.

co-author: Hadrien Grasland <grasland@lal.in2p3.fr>

update LHCb reco scenario and make more flexible graph node type deduction in the scenario assembler