Advanced inventory will now sort via the 's' key, plus other assorted changes and restructuring

* Sorts by: unsorted (order that items were added), by name, weight, volume, and charges. (pending more).
Also:
* up/down in the 'e'xamine window will move to the next / previous
item in the list.
* weight and volume are displayed for ground / car squares.
* Now correctly displays max item per square.