Changes:
- respect post visibility when listing threadmarks (i.e. threadmarks on hidden posts aren't listed)
- more fine grained permissions (see Overview)
- threadmark label length increased from 100 characters to 255
- ensure threadmarks remain on posts when moved to a different thread (note: uses deferred task so threadmarks will take a few seconds to appear in target thread)
- threadmarks button is now clickable to open all threadmarks list
- display threadmarks menu on single page threads
- ensure threadmark still shows after editing a post
- do not show threadmarks dropdown menu when javascript is disabled
- use template modifications instead of deprecated template hooks
- remove unnecessary phrase database queries
Thanks to @Xon for his awesome help with these updates.