Plus update UI (custom)options.
Import custom sites only works from add-ons screen (via icon/popup gives CSP-error). Plus some cosmetic updates in options.
Now delete custom sites from list.
Add your own custom sites (also for testing). Check 'Custom'-link in popup-menu. By default sites' cookies are removed after page loads (to bypass article limit). Also you can enable Googlebot user-agent or disable Javascript for (sub)domain(s).