In trying to fix what looked like a bug in Pushl (which turned out to be a bug in one of the services I was pinging), I did a bunch of much-needed code cleanup and refactoring.

I also added the ability to ping the Internet Archive Wayback Machine for outgoing links if the target has changed (relative to the usual If-Modified-Since/If-None-Match tests).

Pushl will now also log warnings for two useful situations:

• An outgoing link generates a 400-class error (403/404/410/etc.)
• An outgoing webmention has a different canonical URL than what’s being pinged (improved since v0.2.8)

The way it handles canonical URLs is also now improved; if a page has <link rel="canonical"> it will use that, otherwise it will use the final URL that is the result of chasing redirects.