Replace storage model, extend built pages, add theming

[ator-dev]

This PR has grown to encompass many more improvements than it was intended to. Broadly included are:

• Replace storage model entirely to include default values, optional syncing, and other features
  • Requires migration code
• Use page-build system for options page
• Allow custom theming of built pages
• Rename page scripts to remove the -build suffix
• Invert the diacritics matching option
  • Requires migration code