* Speed up the topic listing significantly
* Add 'unread' (short form 'u') to only list topics with unread messages
* Add 'mark_unread' (short form 'm') to mark topics as read without displaying them
* Tweaks to help text
* Default main listing to unread topics instead of listing all topics
* Updates to the way screen dimensions are calculated
* Preliminaary work to support pagination
* Change permissions message from error to warning so it only shows in debug mode