Move and rename EClusterCategory

Place enumeration in StFmsCluster instead of HitCluster, as this is
where the category is actually stored. Rename to EFmsClusterCategory as
it is no longer in a namespace.
Rename Geom files to StFmsGeometry
Rename FitTower files to StFmsClusterFitter
Rename Yiqun files to StFmsEventClusterer
Rename TowerUtil files to StFmsClusterFinder
Rename TowerFPD files to StFmsTower
Rename HitCluster files to StFmsTowerCluster
Rename PhotonHitFPD files to StFmsFittedPhoton
Rename class FitTower to StFmsClusterFitter
Rename class Geom to StFmsGeometry
Rename class HitCluster to StFmsTowerCluster
Rename class PhotonHit to StFmsFittedPhoton
Rename class TowerFPD to StFmsTower
Rename class TowerUtil to StFmsClusterFinder
Rename class Yiqun to StFmsEventClusterer

Resolves #3