New Property: location-visibility

[dshanske]

Related #11

• location-visibility=public (or no visibility set)
• location-visibility=private
• location-visibility=protected

This is based on my implementation in Simple Location, an Indieweb friendly location plugin, of the WordPress Geodata unofficial guidelines. It states a single property which can be set to public or private, with the absence of the property being considered to be public. Proposing the third property, which will allow for a less specific text only display, but no actual coordinates.

This is currently implemented in Micropub for WordPress as a server, and Indigenous for Android as a client.