Fix to use the forum's own permission code instead of reimplementing it on
the getWatchedMessages method. Makes for greater consistency in behaviour.
Some cosmetic changes and fixes for the contact selector form:

- Unselecting a contact in the middle now is done properly
- The contact's are now listed by first name, within departments and
  companies.
- Now there's a label in front of the company selection control, for
  clarity.
- The 'Contacts for' string only shows up if there's actually contacts to
  show.
Additional functionality for the Forum module; now its possible, on forum
or topic creation, to specify which users should watch it.
This allows pushing subscriptions without needing to ask every relevant
user to activate the 'Watch' setting per forum/message.
Anyone who can create/edit a forum/message can change the subscriptions.