In these two games, a potion of monster detection turns on the player's
SEEMONST flag. A fuse is set to call turn_see() to turn the flag back
off. But the save and restore functions do not recognize turn_see() and
fail to set the fuse up again.
When restoring, Rogue V4 merely sets the fuse's function to NULL and
leaves it burning. When it goes off, a segfault results. Rogue V5
clears all the fuse's fields, and the player retains the ability to see
all monsters on the level.
The save and restore code can now handle the fuse. The function used is
a new wrapper, turn_see_off(), which should lead to less problems with
daemons being multiple incompatible types.
Also, Rogue V4 and Super-Rogue now properly clear unrecognized daemon
and fuse slots when restoring a saved game.
In all games, rs_write_room_reference() stored -1 for a nonexistent
room, but rs_read_room_reference() did not check for out-of-bounds
values, leading to pointers to rooms[-1], which sometimes caused
crashes. rs_read_room_reference() has now been modified to use NULL
instead.
Some of the games required further changes to replace NULL with the
pointer to the actual room. Others are capable of handling NULL for
objects not in any room.
