spawn_characters_maybe -> spawn_characters.
guards_persue_prisoners -> hostiles_persue.
character_behaviour_stuff -> character_behaviour.
More spawn_characters_maybe -> spawn_characters.
twentyonelong -> byte_to_pointer.
spawn_character: Make the 'found' label more informative: 'found_empty_slot'.
sub_AF8F: Give a description, fix bounds_check call, return statement.
interior_bounds_check: Revise description, document registers.

And note that $B2BC is a bug.
door_handling_interior: Drop an EX DE,HL which is accounted for.
select_tile_set: Turn a comment into a proper documentation line.
Add a couple of sampled register values.