triggering an impossible warning about "wall_angle: unknown" due
to the known conflict between door state and wall info which both
overlay the flags field for map locations.
Reported and diagnosed by vultur-cadens: if a shop's wall was dug
open, followed by use of locking magic to plug the gap with a door,
and then unlocking that door, the D_CLOSED door flag was left as
invalid wall_info when shop damage was repaired. Map re-display
complained. Leaving the door locked or opening it after unlocking
did not result in any complaint because the values for those door
states do not conflict with wall angle values.
The problem was reproducible and is now fixed by adding an extra
field to the shop damage structure. A similar change has been
made to the vault guard's 'fake corridor' structure but I have no
test case for that so don't know whether it makes any difference.
At least it doesn't seem to have broken anything.
Existing save and bones files are invalidated by the fixes.
Fixes#606
d9bbad8e6e