fix #M107 - blindness and secret doors

From a bug report:  zapping force
bolt broke an adjacent potion of blindness (possibly carried by the monster
he was attacking) which caused "it suddently gets dark" but further course
of the bolt resulted in now blinded hero recieving "a door appears in the
wall".  make_blinded() was deferring vision recalculation until next pass
through moveloop() (or until next pline()--if the "gets dark" message had
been delivered after the call to make_blinded() instead of before, this
wouldn't have been noticeable).  Fix is trivial:  just recalculate vision
immediately when temporary blindness is toggled.  [It might also be needed
for involuntary blindfold removal, although I suspect that that is always
accompanied by corresponding pline() which gets vision back into synch.]

doc/fixes34.4

@@ -126,6 +126,7 @@ chatting with quest leader who was brought back from the dead gave warnings
 becoming green slime or mimicking gold violates "never changed form" conduct
 when a monster grew into a higher form which had previously been genocided,
 	the message explaining its fate was only given if it was sensed via ESP
+hero could still see for brief period after being blinded by potion vapors
 
 
 Platform- and/or Interface-Specific Fixes