Refactor background.js / page.render processor:
  Simplified preconfig settings. Using a simple default color and selector,
  and a list of preconfigured pages, instead of a rather complex preconfiguredPages settings.
  With this change, I can easily create an option page to set up the pages I want.
1. Implement a simple option page to list and delete preconfiged pages.
2. Implement a simple context menu to add current page url as a pattern / preconfig page
Implement a simple local storage solution to save preconfig page into local storage.