Fix double-slam

Looks like the failure-to-judo slam was getting applied even after the
primary slam.  Unfortunately, that's not intended, so nerfing my girls
and boys.

Will buff in due course: thinking the occasional finger-laser guiding a
bolt?
Fix display bug

When showing the first item in the view item list and that item is directly to the northwest of the player, the cursor would not be printed there.
When shifting update map::traplocs

When shifting the map the coordinates of the traps change (as they are relative to the map origin).
They must be updated, just as the submap coordinates of the vehicles must.
Also: return a reference to the traplocation set instead of copying it. For performance.
Merge remote-tracking branches 'dda/pr/8240' and 'dda/pr/8241' into dda-master

* dda/pr/8240:
  Fix double-slam

* dda/pr/8241:
  When shifting update map::traplocs
  Fix display bug