Propagation of changes introduced in !48394 (merged) for rel. 21 into rel. 22.
This includes changes in detector description (AFP_GeoModel, AFP_Geometry); introduction of AFP hit clusters (AFP_SiClusterTools); rewriting AFP Si track reconstruction and including TD track reconstruction (AFP_LocReco). The clustering and track reconstruction were separated (in contrast with !48394 (merged)).
Also switches AFP on by default.
closes AFPSOFT-123, closes AFPSOFT-124, and closes AFPSOFT-125