Adding delete message for threads.
Fixing bug in inbox JS where clicking down into the autocomplete filled in a username
Adding access control to threads
Reorganizing routes to be better in line with APIs
Fixing bug in entering usernames as members, whereby an empty usertag was inserted when leaving the field even when there was no value.
Setting the message form type to be text_long, with the private message inbox display to have the text trimmed to 200 characters.