[Xastir] Online/nationalmap.gov map chooser options.

[Lee Bengston]

I noticed none of the options under "Online/nationalmap.gov" worked, so I
decided to look around at the nationalmap.gov sites to see if I could
figure anything out.  Based on this site,
https://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer,
and clicking the WMS link, I came up with the following, and put it in a
file named US_Topo.geo, and copied it to
/usr/local/share/xastir/maps/Online/nationalmap.gov.  After reindexing the
maps, presto, I got a map.  What's in the geo file is what is between the
dashed lines below.
----------------------------
WMSSERVER
URL
https://basemap.nationalmap.gov:443/arcgis/services/USGSTopo/MapServer/WmsServer?service=WMS&VERSION=1.1.1&REQUEST=GetMap&SRS=EPSG:4326&FORMAT=image/png&BGCOLOR=0xFFFFFF&TRANSPARENT=FALSE&STYLES=&LAYERS=0
-----------------------------
At a high level it appears they have changed to https on port 443, but I
assume libcurl is handling that without issue.

I'll leave it to the developers to decide if they want to look into this
any further, but in the meantime I at least have a geo file that works.  :-)

Lee - K5DAT