Do not search if no letters entered
Set title to 'Nothing found' if... nothing found
Exit search mode on Enter if nothing found
Merge pull request #304 from boris-petrov/search-upgrades

Search upgrades
Use isElementVisible instead of :visible
Change focusFirstTextInput behavior a bit

It should try first to focus a currently visible element, and only after
that try any element anywhere on the page
Fix some bugs with CoffeeScript postfix 'for' syntax
Rename window to w
Add textarea as focusable element
Minor code style
Reset scroll position if nothing found when searching
Merge pull request #305 from boris-petrov/use-is-element-visible

Random fixes and improvements
Optimization in background Bookmark.search
Use KeyEvent.stopPropagation

Instead of returning false from event handlers
Do not cycle non-stop until page is loaded
Do not search bookmarks/history if 'completion_items' doesn't include them
Remove unused extension methods for String
defaultSearchUrl should search in Google if no default
Do not try defaultSearchUrl when opening from clipboard

As it will already be called by fixUrl
Fix editing via external editor