"modelhistory" userstory

[stheid]

The model history should be less a history, but a collection of models available to the participant.
Hence we need the following actions:

• duplicate model
• rename model
• delete model

Deleted models should not be deleted in the database however, but only marked as "hidden"

[stheid]

rename is still missing, however its not clear if modelhistory will remain, hence there will be no work in that regard