Small bit of clarification to item constructors

Since I want to contribute, I figured I would start small with little bits of clean-up and clarification in the code, and then as I learn the codebase more I would like to see if I can reduce the amount of code copy-paste around and help to keep the number of bugs down as well as make it easier to add to the codebase in future.

This simply adds an explicit enum for armour type (boots, legging, etc) to help clean away the 'magic numbers' in some of the code.  If you are open to it, I would definitely like to do more as stated above.