Time for a major update!

Lots and lots of lines of code later, here is the new version of the ProTheme. Changes:
- CSS rewritten in SCSS, using the Compass framework. It is now extensible, modular and easy to edit.
- Introducing font awesome icons: bye bye old and heavy images. Every icon has been replaced with its font awesome counterpart, excluding the country flags which are expected to be replaced in a later update.
- Disabled protheme-wide the markdown support. Will be enabled when the new library is completed.
- No more inline styles for posting forms - now there are classes for each post control: 'post-control-textarea', 'post-control-submit', 'post-control-preview' (which replaces 'preview'), 'post-control-bbcode'.
- Due to the CSS rewrite some tweaks to the stylesheets have been made - let me know if something is wrong.
- Normalize.css has been removed: NERDZ looks better without any CSS reset.
- The remove comment icon has been removed to and its animation has been changed.
- Completely rewritten the method responsible of editing the posts.
 More information about font awesome can be found here: https://fortawesome.github.io/Font-Awesome/