New layout, depending on screen width

Better layout for both wide and narrow screens, using CSS3 media queries.
Pager now with position:fixed; centered and highlighted
Improved optics of long tag lists
Let form elements adapt to different screen widths.

Especially adapt textareas and fix line breaks in evaluations.
Create standalone tag editor for small screens.
Added Font Awesome and used it in some headers.
Added separate menu to header/panel

Menu appears in header or panel depending on screen width.
Redesigned header

Adapt coloring and popup login form for narrow screens.
Enhanced CSS for panel

Made it fixed, provided sufficient width. Also, don't show embeddings on
narrow screens.
Redesigned buttons

Added symbols, minified for narrow screens and moved to the inner side on
task.php.
Enhanced user table; marking head, body and foot
Small corrections
Enhanced headers in form pages

They now work independent of specific font metrics.
Enhance publishing form
Removed captions and reordered elements on the task page
Overhauled comment list in task page
Redesigned filter form without tables
Small corrections
Merge branch 'redesign'

Lots of conflicts arised because we changed all links in master. And we
changed the head in redesign, which was factored out in master.

Conflicts:
	eval.php
	head.php
	index.php
	problem.php
	solution.php
	tagpanel.php
	tags.php
	task.php
	tasklist.php
	user.php
Some fixes.