UltraRogue: clear the next_obj field when removing items from the floor. The next_obj field is a pointer which the top item in a stack uses to keep a list of the other items. When removing an item from the stack, rem_obj() failed to set next_obj to NULL, which can cause items in monster inventory to point to items earlier in the inventory list. That causes infinite co-recursion when saving or restoring.

[Desktop Entry]
Encoding=UTF-8
Name=Rogue
GenericName=Rogue
Comment=The original curses-based adventure game
Exec=rogue
Icon=rogue.png
Terminal=true
Type=Application
Categories=Game;RolePlaying;
Version=1.0