closes #69

update to "create" scope by default, but allow the user to choose "post" as a fallback. also updates indieauth/client to 0.2 for json support.

* 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

allows backdating and future-dating posts

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

fixes #9

fixes #42

replaces #56

fixes #50

fixes #48

* 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

Also set the theme color for Chrome to the blue used
in the logo.

Firefox picks up the last defined icon PNG for the add to
homescreen feature - https://bugzilla.mozilla.org/751712

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