(open) Change Request; Implement LUA function trim.TrimSelected()

[Bletchley Park]

Please implement the function trim.TrimSelected() where a trim is applied to all currently selected residues, this should override any previously selected and trimmed residues, whether manually or LUA selected.
This will help us craft new automated methods for efficiently exploring large Electron Density puzzles.
Likewise this will require a function trim.UntrimAll() which will untim all trimmed sections.

[man_the_stan]

Should recipes also be able to query which subset is currently trimmed? I think that would be wise.