fix github issue #581 - "You see no door there."

Year old issue from copperwater:  'open' directed at a non-door told
player that there isn't a door and took no time unless character was
blind and learned what type of terrain it is, applying a key gave
the same message but used a turn and didn't update map to reflect any
terrain discovery.

Attempting to open an adjacent door or applying a key to one while in
a pit had a similar issue:  they produced the same "you can't reach
it from here" but had different time vs no-time outcome.

There may be other actions in the same situation.

Closes #581

doc/fixes3-7-0.txt

@@ -1024,6 +1024,11 @@ room stocking would put multiple items on the same spot
 splitting a stack of named, shop-owned objects while perm_invent is enabled
 	produced impossible "unpaid_cost: object wasn't on any bill."
 more consistent feedback if a reviving corpse becomes an unseen monster
+improve consistency between applying a key and explicitly opening a door:
+	if in a pit, you're told "you can't" and no time elapses; if there
+	isn't any door in the direction supplied, you're told "no door" and
+	time elapses if you discover the non-door's terrain type but doesn't
+	if you already knew the type there
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository