Update code because of Stamen discontinuation

[vincedchart]

Stamen tiles being now unaccessible, no map shows up with this yet GREAT plugin.

for it to work again, everyone has to update code at least in files:

• leaflet-providers.js
• open-map3.tpl
• functions_map.php

changing a Z X Y tile provider stamen when you spot it, with

https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png

or ://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png

[vincedchart]

suggesting fix

[vincedchart]

sugges