Traj float

This PR contains two components:
1)
change double to float in LocalTrajectoryParameters.
for TTBAR 40PU25ns  I observe a reduction of ~100MB of RSS for a very-small regression and no changes in tracking performances
No clue why was not done before (most probably less relevant at low pileup)

2) add "pt" to PTrajectoryStateOnDet
the original idea was to be able to access the "pt" of a seed w/o converting to a TSOS
it turns out that sorting seed in pt does not improve anything.
I prefer to keep it around for a couple of pre-releases, eventually remove (and clean code) if not useful in any way