Fixed being able to add post relation to itself
Moved "upload anonymously" checkbox below "source"
Improved input alignment in forms
Improved support for small screens in upload form
Added protection against unsupported URLs
Fixed thumbnails for non-image uploads
Changed behavior of post list tabs

Before: each one linked to separate page that contained "static" search.
After: each one links to generic search that is aware of current search.

Example: if you searched for "snow" and clicked "upvoted", you would see
all upvoted posts ever regardless of what you just searched for. After
this change, you will see upvoted posts that have tag "snow". Now, if
you go back to "all posts", you will see again all posts tagged with
"snow" with or without the upvotes. Similarly if you click favorites,
favmin:1 will be appended to your search. In order to totally reset your
search, click "browse".

Additionally, typing favmin:1 and scoremin:1 manually now selects proper
tab.  Previously tabs were marked only if you clicked the tab.

Unfortunately, all of this had to happen at expense of URLs like
/upvoted and /random - now everything is represented with plain /posts/.
Removed global Javascript variables
Improved next/prev post behavior