v1.7.3 — Backing up or restoring a long history no longer runs the phone out of memory; both stream a piece at a time, with progress on the map, and an export finishes even if you close the settings panel. Two backups at once no longer overwrite each other's files, a login the server rejects is dropped after a few tries, and the daily backup runs when Android denies it a foreground slot. A restore keeps each point's terrain, and a fog recompute fills it in for older points. GPX exports write pla