Add z member to StMuFmsPoint

This allows the full 4-momentum to be reconstructed from (x, y, z)
coordinates and the energy, saving us from additionally writing the
momentum vector.
Add StMuFmsPoint constructor from StFmsPoint
Separate method in StMuFmsUtil to fill hits
Separate method in StMuFmsUtil to fill clusters
Separate method in StMuFmsUtil to fill points
Remove return statements from void methods
Separate StMuFmsUtil method to fill StFmsHits
Simplify function to set StFmsHits
Add StMuFmsUtil method to fill StFmsClusters
Add StMuFmsUtil method to fill StFmsPoints
Add method to set StMuFmsPoint from StFmsPoint
Set StMuFmsPoint properties from StFmsPoint
Return hit from StMuFmsCollection::addPoint()
Use new addPoint() syntax

Protect against NULL pointers before assignment
Add xyz() method to StMuFmsPoint
Add momentum method to StMuFmsPoint
Add 4-momentum method to StMuFmsPoint