Chrome can't executeScript on file:// URLs even though we have <all_urls> in manifest.json so on such pages we'll display a warning in the popup. This should only happen when Stylus is [re]enabled/reloaded.
* update state is shown in tooltips that fade out in 10 sec except for .update-problem and .can-update
* when updates are found a filtering option is revealed; when it's checked only entries with updates are shown; when all updates are installed the option automatically hides
* Now that our own pages retrieve the styles directly via getStylesSafe the only 0.001% of cases where code:false would be needed (the browser is starting up with some of the tabs showing our built-in pages like editor or manage) is not worth optimizing for.
* According to CSS4 @document specification the entire URL must match. Stylish-for-Chrome implemented it incorrectly since the very beginning. We detect styles that abuse the bug by finding the sections that would have been applied by Stylish but not by us as we follow the spec. Additionally we'll check for invalid regexps.
* [x] show badge with active styles count
* [x] styles on top in the popup
* Simplify since we use a persistent background page so it's always there for us
(1) Add UI controls for `keyMap`, `tabSize`, `indentWithTabs`, and
`lineWrapping`; `indentUnit` tracks `tabSize`.
(2) Dispatch `change` events from `loadPrefs` to initialize CM options
from the controls' event listener.
(3) Move stock options from the `CM.fromTextArea` call into `CM.defaults`.
Add `CM.setOption` method, analogous to the instance method, which updates
`CM.defaults` and sets the option in all instances; add `CM.getOption`
which simply returns `CM.defaults[option]`.
(4) Move the new editor functions into `CM.commands` and replace the
functions with commands.
