Vehicles block acid fields
Removes muzzle gunmod location on revolvers
Create constants for bounds of scentmap in for loops.
Whitespace formatting for grscent assignment readability.
Rename bool matrix has_wall_here to blocks_scent.
Rename bool matrix reduce_scent_here to reduces_scent.
No need to compare bools to bools.
Additional comments and some rewording.
Pre-increment instead of post. Bleh.
Merge remote-tracking branches 'dda/pr/9814', 'dda/pr/9815' and 'dda/pr/9817' into dda-master

* dda/pr/9814:
  Vehicles block acid fields

* dda/pr/9815:
  Removes muzzle gunmod location on revolvers

* dda/pr/9817:
  Pre-increment instead of post. Bleh.
  Additional comments and some rewording.
  No need to compare bools to bools.
  Rename bool matrix reduce_scent_here to reduces_scent.
  Rename bool matrix has_wall_here to blocks_scent.
  Whitespace formatting for grscent assignment readability.
  Create constants for bounds of scentmap in for loops.
Document why we're shutting off acid damage.