fix another 'wonky secret door'

The cavemen quest description includes an 'S' in the lower right
corner of the MAP...ENDMAP section of the locate level.  It produced
a secret door as intended but did not have horizontal vs vertical set
because the latter was only being done for DOOR directives.  Instead
of adding an explicit directive, make the loading code set horizontal
vs vertical for all doors.

This fixes the orientation of that secret door in the Cav locate
level, but I noticed that it showed up an a visible horizontal wall
when the spots on either side were still blank.  It's behaving as
if the door is on a lit spot and the adjacent walls are unlit (this
misbehavior was already present before the current change; it was
just shown incorrectly as a visible vertical wall before).

doc/fixes36.1

@@ -605,6 +605,9 @@ the fix for secret doors on special levels always having vertical orientation
 and the previous fix for the for secret doors didn't work if the level hadn't
 	been wallified yet (Cav quest) so horizontal wall with secret door
 	mis-displayed as a vertical wall segment could occur
+and both the previous fixes only worked if the level description contained
+	an explicit DOOR directive rather than just '+' or 'S' on the map
+	(as with lower right area of Cav 'locate' level)
 the fix intended for "a shop object stolen from outside the shop (via
 	grappling hook) would be left marked as 'unpaid'" broke normal pickup,
 	preventing any picked up item from merging with compatible stack