Missing INCs

There are two .INC files, ROOMNUMS.INC and DSMI.INC, which are missing from the repository. These files are presumed lost, but this problem can be worked around.

DSMI.INC was the interface to a third-party sound library. It should not be necessary for a port; if it's necessary to compile the original, the routines can be stubbed.

ROOMNUMS.INC contained symbolic constants for all the rooms in the game, mapping their names to their serial integers. If needed, I can recreate this file without much difficulty.