Collaboration: migrate from 1:M to M:M connections between users and topic maps

[brettkromkamp]

In addition, track permissions (i.e., can-view, can-edit and can-comment) and ownership on the connection between a user and a topic map.

[brettkromkamp]

This change will have large consequences downstream (i.e., Contextualise).

[brettkromkamp]

Done.