Get ALKIS added to the Straßenbefahrung Layer (Make strassenbefahrung Layer transparent)

[tordans]

Goal: A view like FIS Broker uses it

https://fbinter.stadt-berlin.de/fb/index.jsp?loginkey=zoomStart&mapId=k_StraDa@senstadt&bbox=394470,5814931,394581,5815003

This commit 9480849 does work in the sense, that both services are requested in the logs:

• https://fbinter.stadt-berlin.de/fb/wms/senstadt/wmsk_alkis?format=image%2Fpng&layers=30,5,21,0,29,4,7,13,9,25,8,18,20,16,28,12,24,22,34,26,47,46,44,43&style=default&transparent=False&bbox=386328.23088747164,5815662.014271956,386548.86334531097,5815882.121432388&width=1187&height=1184&request=GetMap&version=1.3.0&service=WMS&styles=&crs=EPSG%3A25833
• https://fbinter.stadt-berlin.de/fb/wms/senstadt/k_StraDa?format=image%2Fpng&layers=68,67,66,65,64,63,62,61,60,59,58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1&style=default&transparent=True&bbox=386328.23088747164,5815662.014271956,386548.86334531097,5815882.121432388&width=1187&height=1184&request=GetMap&version=1.3.0&service=WMS&styles=&crs=EPSG%3A25833

BUT the Straßenbefahrung layer is not transparent in this example request and as such does not allow Alkis to show in the space between.

I reverted the commit for now to not cause double the traffic for nor reason.

[tordans]

This was done in https://github.com/codeforberlin/mapproxy-config/tree/master/demo_links for a few sources.