Refactor editusersingroup.cgi

* Show indirect grants
* Show bless permissions
* Allow to remove users from group
* Allow to add/remove users if you have bless permission for it, not only if you're in 'creategroups' group
* Allow to grant/revoke bless permissions if you're in 'editusers' group
* Add link to editusersingroup.cgi from "Edit group" page
Allow to go into editusersingroup.cgi from Administration->Groups