Remember last custom tile layer

[oiva]

When selecting a custom tile layer a prompt is presented asking for the URL of the tiles. If you change between an aerial imagery layer and the custom layer you need to enter the URL every time.

The editor could remember the URL you used last time for the custom layer, and pre-fill the JavaScript prompt withe the URL.

[mikelmaron]

+1 to this issue.

Or even not prompt, unless you click another link within the selection box.

[tmcw]

Duplicate #1756

[tmcw]

Er, I guess this is for custom tile layers so is a little bit different.