* feature: In adoon's configuration dialog, enable to open the prompt dialog box to edit the adittional style text. In the previous version, user bothered to invoke the preference manager.

* bugfix: On start editing the pre-saved mail that has some recipients, some fields were not colored correctly.
* feature: In configuration dialog, add textbox for directly specifying the color code
* feature: Enable you to customize any other styles in adittion to background-color. But no UI for editing, so use preference editor. You can write any other CSS styles to extensions.coloredrecipienttype.*.style, but too arrogant styles might destroy the compose window.