Add OpenstreetMap tiles

[ccloquet]

• useful for fire brigades in rural areas, but in cities as well

• ask for permission

• consider deploying own Mapnik style tile server

cf : https://operations.osmfoundation.org/policies/tiles/

TODO :

Clearly display license attribution. (cf https://www.openstreetmap.org/copyright) Add a link to https://www.openstreetmap.org/fixthemap to allow your users to report and fix problems in our data. If known, a valid HTTP Referer. DO NOT send no-cache headers. (“Cache-Control: no-cache”, “Pragma: no-cache” etc.) Cache Tile downloads locally according to HTTP Expiry Header, alternatively a minimum of 7 days. Maximum of 2 download threads. (Unmodified web browsers’ download thread limits are acceptable.)

[ccloquet]

-> permission asked, waiting for answer