P0-A6: Part 703: Inventory System

The inventory system is basically done, in concept.

I have just added support for carrying four items, but the core concept is working well. I should be able to add support for at least 8, maybe 10 items without any major difficulties.

I have also found a way to simulate very low visibility, or “whiteout” conditions, which would work well for blizzards, snow storms, etc.