Clean up new reply handler function.
Split user subscription stuff out of handler functions into separate functions.
Move some non-template topic functions over into functions-topic.php.
Consolidate template query functions `mb_has_*()` and `mb_*()` into a single `mb_*_query()` function for each post type.
Clean up template-topic.php.  Add inline docs.  Rewrite some code to make it better.
Add reply spam template functions. Note these don't actually do anything at this point except for output HTML.  The spam functionality is still in the works.
Remove old forum meta functions.
Move functions from template-forum.php that aren't template related.
Recreate many of topic template tags for forums.
Separate many of the includes files into their own folders for better organization.
Better organization of includes files.
Re-add 'forum-link' class.
Move template-post.php to common/template.php.
Consolidate pagination functions.
Clean up is_paged functions.
Formatting functions update.
Register *_datetime_epoch meta.
Remove old term meta functionality that was commented out.
Add function for resetting all reply positions (menu order). Make sure reply queries are ordered by menu order.
Change reply URL system to something a bit more efficient than what we were using from the bbPress plugin.

Note: Remember to ping @johnjamesjacoby on whether he might be able to use `mb_reset_reply_positions()` in bbPress.