+ Add ability to report user profiles

This batch of commits does three things:
1. Removes the "email the user through the forum" option (closes #1403)
2. Adds the ability to report user profiles to anyone with the "moderate_forum" permission (fixes #1383)
3. Fixes a few bugs with the "Report to Moderator" feature that were found while testing the new feature

Note that the first part was supposed to be a separate PR, but I forgot to submit a PR for it and it's too much work to fix it now due to the large number of changes involved.