Adding get_ux_context() and related

… and speeding up processing by using window.wp_pressthis_config if set
in markup (avoids a remote script inject) already, which will be done
at load time. LocalStorage settings will still take precedence (for
now?).
Tools batch!

* Start of site instance select/edit/add/del menu (hidden onload for
now, still ugly)
* Added form to add a URL to scan and made it work
* Speeding up bootstrap time by outputting window.wp_pressthis_config
in markup on server-side load, which avoids one remote connection (when
fastest localStorage doesn’t kick in 1st)