TODO

Refactoring

- (more) testcases
- complete the documentation, publish generated jsdoc

Readability/Filters

- detect if the full article text is present in excerpts
- manage to use the readability dom tree for filtering

Proxy/Server

- cache the rss feed (use etag/since from server or own caching rules)
- support gzip content compression
- support etag caching
- detect images (and maybe other content) and download it locally so that the
  proxy can serve it from cache.
- support http and socks proxies for urlopen

Cache

- gzip the cache files
- support database caching

Crawler

- fetch and respect the robots.txt file