tiny cleanup
skeleton of generic update dialog
collect and (half) populate fields
fine-tune form construction and pre-population
working update implementation -- issues with detecting change in ModelMultipleChoiceFields
update working with little issues: clearing of fields cannot be forced and choicefields have to be changed to some other value than the first.
better treatment of ChoiceFields
plain ChoiceField treatment; does not apply to ModelChoiceFields
still needs bugfix for ProteinComponent and others