issue #20549: added grpext table
issue #20549: added user account role extension orms
issue #20549: added client-side models
issue #20549: added assignment box
issue #20549: doc
issue #20549: UI for interaction between role extensions and user extensions
issue #20549: bugfix
issue #20549: extension route looks at role-granted extensions
Merge pull request #498 from shackbarth/20549-grpext

issue #20549: users can get extensions from group