Prefer imagery marked as best in editor-imagery-index

[bhousel]

• Sorts the best imagery at the top of the background list
• Pick it automatically if the url hash doesn't specify an imagery source
• Also bump "none" to the bottom of the list
• re: Suggest alternate imagery based on map location #2826 Per country default background #1310

cc @pnorman @planemad @lxbarth thoughts?

Before	After
#map=14.96/8.2276/47.5272	#map=14.96/8.2276/47.5272

[planemad]

@bhousel awesome! does it switch by default to the best imagery for a location on opening iD?

[bhousel]

Yes it will try to pick the best one - as long as the url includes map coordinates and doesn't include something like background=Bing

[planemad]

👍