Link Status WE per emk

Update: Link Status Redux 3.0 migrated to WebExtensions.

This is a WebExtension port of Link Status Redux. See the description of Link Status Redux for more details. Due to WebExtensions API limitation, this extension could not port some features:

• The "Disable visited link styling" option is no longer present. Flip the "layout.css.visited_links_enabled" pref manually from about:config if necessary.
• You will have to hide the browser native status tip manually. Add the following style rule to userChrome.css:
  statuspanel[type=overLink] { display: none !important }