#192 Tables do not sort with underlying objects

[Fogh]

Try to open Sec5Part3.ccpn, as stored in internal/data/starExamples/testProjects, and look at the ChemicalShift table. There is no way to sort the table according tothe underlying ChemicalShift object. The '#' column is the serial of teh attached NmrAtom resonance (not hat we want), and clicking on ay column sorts by string sort on teh column values. We want an easy - and probably default - way to sort by the sort key of the ChemicalShift object, which has been carefully optimised to sort as fits the data. The same problem is liley present for other data typpes too.