fads-app: introduce -evtmax flag. defaults to -1
fads-app: streamline container names. fixed propagator props
propagator: recompute radius2 value in Configure
propagator: fixed propagation along z-axis
propagator: more straightforward computation of sign(pz)
pprop: fix (math) typos
makefile: pass -evtmax=-1 to fads-app
propagator: sort particles by descending-pt
hepmcreader: sort output particles by descending-pt
hepmcreader: heppdt.IsStable's definition isnt the same than TParticlePDG => use ROOT's convention
calo: proper impl. also: Calorimeter -> calorimeter
fads-app: specify MomentumOutput and EnergyOutput for track-merger
fads-app: add eflow-merger
all: fwk.Error -> error + gofmt