U338 - dismounting into known traps

When dismounting by choice and not impaired, the player could end up in a
known trap even if better positions were available.  This change allows
the landing spot to prefer non-traps in these cases.

doc/fixes34.2

@@ -90,6 +90,7 @@ use correct pronoun for unique monsters
 hostile monsters who follow you between levels won't do so if they're fleeing
 options for font_size for map, menu, message, status, and text all had the 
 	same description of "the size of the map font" in options.c
+when dismounting by choice and unimpaired, try not to land in a known trap
 
 
 Platform- and/or Interface-Specific Fixes