subtle usability updates and icons etc
added icons to all interfaces where possible
styling icons in front of headings in header bar
added alternate search areas to main search results
forgot to translate strings added in my previous commit
updated horizontal rule icon to use a more appropriate char
fixing horizontal position
Merge branch 'master' into ben-design-change
Merge branch 'master' into ben-design-change
tweaking userbar to suit slight alteration to icon layout behaviour in this branch
  Patched the migrations and wagtailusers app to add better support for custom AUTH_USER_MODEL
Added template tag slugurl

Added a new tag that returns a page URL according to the page slug.
quality of userbar js improved. also now checking origin to prevent postmessage listener trying to act on messages from other domains e.g vimeo
Forcibly delete the sessionid cookie on logout.

This means that we can use its absence as an indication that front-end requests are being made by a non-logged-in user and are thus safe to cache (i.e. don't include the editor toolbar).
Merge branch 'master' of github.com:torchbox/wagtail
Updated breadcrumb and explorer style. Added vary_on_headers wherever ajax search results are returned. Added icons to headers where previously missed.
view draft/view live now simply draft/live
added title tag to ellipsis items in edit page breadcrumb
resolved merge conflicts
sped up userbar fadein