Micro optimalizations

Saved 0.015s on various things, mostly thanks to new chibi-core caching
Merge remote-tracking branch 'upstream/master'
Fixed silly bug

Statistics for each user in user list showed comment count instead of post
count.
Merge remote-tracking branch 'upstream/master'
Fixed invalid SQL in some circumstances
Last comments respect safety choice
Merge remote-tracking branch 'upstream/master'
Misc CSS tweaks
Merge remote-tracking branch 'upstream/master'
Fixed problems with block-level spoilers

Block-level spoilers (= inside <h1>, <li> etc.) were left unparsed.
Merge remote-tracking branch 'upstream/master'
Markdown: disabled atx-style header support

Rationale - collision with tag syntax: if #tag was first word in given line,
the line was treated like header.
Merge remote-tracking branch 'upstream/master'
Edit tokens moved to model
Added comment editing support

In other news, editing a post doesn't reload page anymore
(yay for editing tags for Youtube posts)
Merge remote-tracking branch 'upstream/master'
Slightly changed comment edit log message