Maybe introduce TrackerHitInfo etc utility classes for links
Time resolution in tracker hit
Use 4-vector + 4D diagonal covariance for tracker hit
Remove redundant "polar" components - could be moved to Info utility class if useful
Remove most of the ExtraCode for explicit constructors - this should either be a main Podio flag, but won't be necessary in the presence of the Info utility classes
Rename RICHCluster to RingImage or similar
Simplify some of the ExtraCode to make yams file look less scary