Checkpoint with several changes, committed so Stas can play with debug code.

1. Change planet member of quadrant struct back to integer so it can be saved.
2. Add code for torpedoing an inhabited world.  Score drops by 400 when you
   do that, it's the only outcome worse than being killed.
3. Events are now structures and can hold quadrant coordinates.
4. EXPERIMENTAL tag is gone, code for BSD-Trek events is in good enough
   shape to test now.
5. User input is always logged.
6. SEED command is implemented.