2 updates to functionality and 1 bug fix

KyleWM is using a webmention endpoint as a relative url '/webmention' which obviously was not working.  I added a bit to check if the endpoint is relative and correct it if so.

I added an ability to return the text from the debug messages by a call rather than only output to console.

I added the ability to get back any URLs returned by webmention clients.  This is very useful for brid.gy integration as I get the syndication links it returns to me.