rogue4 and rogue5 set the player's ISRUN flag upon exit from sleep or
holding. This is apparently supposed to indicate that the player can
move again. What it actually does is make it harder for monsters to
hit the player, until the flag is reset.
As this behavior makes little sense and seems like a cheat, it has
been deemed a bug and removed.
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.
