Added [P] hotkey for selecting first post on page
Changes to infobar in post thumbnails
Post view actions don't reload the page anymore
Low-level refactor to core.php
Fixed sending empty comments
Fixes to Markdown

- aa_bb cc_dd doesn't produce italics anymore
- asd@5.com doesn't produce link to post 5
- asd.com#anchor doesn't produce link to tag "anchor"
Fixed logging of post previews
Closed #61
Closed #57