let's give this a shot

closes #71

* now you can enter alt text for photos. see https://www.w3.org/TR/micropub/#uploading-a-photo-with-alt-text for details
* if the note has alt text, then the request is sent as JSON instead

* adds setting to choose the property to use for the syndication targets
* all existing users default to the old value `syndicate-to`
* new users default to `mp-syndicate-to`

closes #66

closes #61

closes #62

* shows reply context of the URL you're replying to
* autocomplete nicknames from the post when replying
* moved debug info to the settings screen to clean up the UI

* looks for a media endpoint in the micropub config
* if media endpoint is available, both the note interface and the editor will upload files to it instead of posting the photo directly
* the note interface autosaves in-progress notes in localstorage

The `#note_photo` form element is the only instance in the application
that used the attribute.

Accidents happen, you shouldn't have to refresh the entire page
to get rid of the image.

closes #36

Quill corrects the photo rotation based on exif data since iOS tends to take landscape photos and set the rotation bit when holding it in portrait mode.

Support reply bookmarklets, and hopefully the Firefox Social API
"Share" provider too.

* disable facebook liking for now since it was getting complicated
* new page for creating a favorite, can pass in a URL parameter too
* bookmarklet code added to the "favorite" page