Implementation of CMSSW-like features to mkFit fitting

[cerati]

mkFit fitting currently lack some features that are in CMSSW and that we may want to implement (although we do not want to implement all features of CMSSW):

1. creating a TrackExtra, including saving outermost state (for propagation to calorimeter)
2. filling of HitPattern
3. some sort of outlier rejection