Switch the access_point-minor icon to key off of backcountry=yes

[scarapella]

The access_point-minor POI icon exists to indicate waterway=access_points that are more in the backcountry and might be used as start and/or end to portages, access to islands etc. Today this keys off of the parking=no tag.

After some discussion with @quincylvania, I would propose that using backcountry=yes (in the sense of "access is by non-motorized means") on these waterway=access_points is a more explicit indication. While parking=no is invariably true when backcountry=yes, there are other access points where parking=no and backcountry=no e.g. those which are shuttle or transit accessible, but do not have parking facilities.

[quincylvania]

@scarapella Thanks! Looks like the data should already be in the tiles.

[scarapella]

@scarapella Thanks! Looks like the data should already be in the tiles.

yeah, I was super happy to see that. Someone... having foresight saved me a bunch of time ;-)