Fixed an edge case and simplified code

When project and language filters choices were cleared, it was failing to
perform the redirect to the root.
Moved editor search box to action links

This also adds the new "Go back to project browser" action link in the
editor's page, which returns users to the original page they entered the
translation mode from (takes into account some contstraints).

Fixes evernote/pootle#77 and fixes evernote/pootle#83.

Pick notes: Fixed some conflicts due to code divergence, in particular the
    translate actions being displayed using JavaScript instead of
    templates. Also regenerated the sprite.

Conflicts:
	pootle/static/css/sprite.css
	pootle/static/images/sprite.png
	pootle/templates/browser/overview.html
	pootle/templates/editor/main.html
	pootle/templates/home/base.html
	pootle/templates/languages/base.html
Adjust back action icon alignment
Don't display senseless message
Partial pick: Cleanup: prefix JS selectors

Pick note: The rest of the changes is not necessary-

Conflicts:
	pootle/templates/browser/overview.html
Preserve query strings in home redirects
Redirect to the project browser after going through all units

Also fixes a bug where using keyboard shortcuts would trigger navigation
the same way as if a submission was made.

Fixes evernote/pootle#87.
Rename action "Back to overview"