* recognize changes in applies-to inputs
* recognize changes only in specified controls
* forget the dirty applies-to ids from a deleted section after the style was saved
* toMozillaFormat: use the actual contents of CodeMirror instances
* toMozillaFormat: allow empty code section with non-empty applies-to
* refactor: simplify, de-kludge, de-duplicate, de-obfuscate, use more descriptive names instead of "items", "a", "b" where appropriate
An element with a `defaultValue` now becomes dirty when removed; elements
without become clean. As a result, removing an existing section makes the
document dirty while removing a new section makes it clean(er).
(1) Record initial value of text, select, and checkbox elements and re/set a
dirty class on each when the value changes.
(2) Combine the individual flags into a global dirty flag.
(3) Add 'dirty' status to the document title.
(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.
Styles are listed before actions by default. Actions are listed before
styles if `popup.stylesFirst` is false. A control for the option is shown
in "Manage" if `popup.stylesFirstUI` is true.
Two independent filters. One allows only styles that are enabled, the
other allows only styles that were written locally (that is, styles
without an update URL).
