Add support for mp q=config destination

[EdwardHinkle]

Add support for destination configuration. From a UI perspective, posting to multiple micropub endpoint versus posting to a single micropub endpoint with multiple destinations should be the same.

indieweb/micropub-extensions#3

The one part to think about is defaults. How should I default the destination? Should it be the first destination in the list or the last destination used? I currently allow someone to set a default Micropub Endpoint, but a default Destination is different. Maybe that’s the answer, maybe if they have more than one destination, I need to allow an option to choose a default destination on the micropub endpoint settings page.

(Originally posted at https://eddiehinkle.com/2018/02/20/12/reply/)

[aaronpk]

This is exciting. This will motivate me to work on the multiple destination support I have in mind for my website!

[RosemaryOrchard]

Maybe we need to set a standard for defaults? In the endpoint I've been writing if no destination is set I have a default one in the background, and that should be the first one returned in the destination list - unless said list gets alphabetised of course.

As I see it, it might be goo to have 2 defaults: One returned by your endpoint, and one stored in Indigenous (so by default my endpoint might post to /micro but I want Indigenous to post to /links.

Of course, supporting the destinations which are attached to the channels in Aperture would be nice too, and remove the need for default handling on your end perhaps?