make the "Assign to workspace" command more powerful

[Malte]

If i accidentially create a "Person" topic in a private workspace but want to have it public i must reveal the complete composite topic (that is: all its direct composite childs with their resp. associations) and "Assign to Workspace" on all these items manually.

Following down the "composition" association this should all be possible automatically in one "Assign to workspace" command, otherwise the "Person" ends up in a public workspace without "First Name" and "Last Name" data, etc.