Provide URL parameter which limits the groups exposed in a profile create / edit form to a single group AND include group descriptions when available

1. When a profile is used for Mailing List subscribing, users want the ability to expose only a specific group when the "Group(s)" field is part of the profile. Implement a mechanism similar to the 'gid' parameter which can be added for mailing/subscribe - but we need to use something other than gid since gid is the Profile id ("grid"? or "group_id"?). If this param is included, only that group is included in the checkbox set.

2. Include Group Description after the Group Title if one is provided. (Best approach would be use use a table for checkbox, title, description as we do in mailing/subscribe.)