Do not fail on incorrectly encoded files.
Make output less verbose for now.

Needs to support configuration. Or duplicates should simply
be filtered out earlier, never making it to the queue.
Parser tests: add additinal check that we don't lose data.
Fix html parser edge case.
Make HTMLParser accept strings as input.
Refactor Link.resolve().

Now needs to be be given the session/spider reference, rather than
the Link object being attached to one.

This paves the way for new functionality that requires access to the
spider/mirror within resolve(), and I prefer this to attaching the
actual spider instance to each link.
Support Expires, option to not check for updates.