add support for webmention v0.2's canonical rel="webmention"

[snarfed]

retains backward compatibility with rel="http://webmention.org/"

the inspiration was trying to reply to one of tantek's posts, since tantek.com only has the rel="webmention" link.

[pfefferle]

Thanks, but I am working an a completely new version of the plugin that only implements the webmention spec (https://github.com/pfefferle/wordpress-webmention/tree/experimental) and moved the mf code to this plugin https://github.com/acegiak/Semantic-Linkbacks

[pfefferle]

I should merge the code to the main branch asap.

[snarfed]

ah! ok, sounds good. hopefully the new plugin will still do backward compatible discovery! there are plenty of sites out there that still have rel=http://webmention.org/, and it'd be a shame to lose support for them.

regardless, good luck! let me know if i can help!

[pfefferle]

Yes, it adds and discovers both.