Make category cohorts visible sitewide for site administrators

If cohorts are created at the system level they are visible to administrators - but this potentially means long lists of cohorts for course editors to sift through. The existing functionality to define cohorts at granualar level within categories therefore makes sense - but becomes difficult for sitewide adminstrators to keep track of and support. If administrators could view all cohorts in .../cohort/index.php along with system cohorts it would make this much easier to manage. They wouldn't need to be always visible - either a toggle button to 'view all' or category menu to see from a dropdown where cohorts have been created. The ability to move cohorts from one category to another in same way that courses can be moved would also be useful.