[Xastir] downloading from tile.openstreetmap.org

[David Brooke G6GZH]

I recently did a fresh install, so had no cached tiles, and found that
the OSM_tiled_mapnik tiles weren't successfully downloaded.

It turns out that the tile.openstreetmap.org server is issuing redirects
from http to https which are apparently not being followed by xastir.

I worked around this by changing the URL in the installed
OSM_tiled_mapnik.geo file from http to https.

If this is considered a correct solution then maybe it could be updated
in the distributed files, though I'm not sure why the redirect is being
ignored.

David G6GZH