Added

Extension version for the Chrome browser platform.
Support for Firefox for Android.
Dark theme for the popup. Switching to a light/dark theme is determined by the selected browser theme.

Changed

Switch sources to TypeScript from Flow.js typings.
Fix subscription links: aggregator now URL-encodes feed URL in it.
Stop considering XML sitemaps as feeds (#4).
Put the direct feed URLs in the links within the popup instead of a link encoded for the aggregator, so they are easier to preview on hover.