- Added missing insertpre plugin and allow <pre> tag with class
attribute. Added font style to base.css.
- Removed unused link to old ckeditor.css (now managed by
django-ckeditor).
- rename static subdirs to css and js
- move global static dir to core/static, changed
- move global templates dir to core/templates
- check comments and code style of all our own CSS and JS files
- minor changes related to the changes of template and static files