* Add open/hidden group membership display and remove
* Include requestable groups other than open
* Prevent users requesting or leaving non-joinable groups
I have not prevented users joining hidden groups however, as
there may be some use cases where the direct link is provided
for users to request access to the group.
Also prevent users generating leave requests for groups they
are not a member of.
* Refactor Group extension models into a single OneToOne model
Added group leader field
* Add blankable fields
* Switched to use navactive for menu highlighting
* Consolidate member state checking for easier code reuse
* Added support for group leaders to manage groups
* Added info log when a user removes someone from a group
* Add ordering to group member list
