Implement Abstract item classes, and derive armor/weapons from it

[aPruner]

• Pretty self explanatory
• Need to decide on which data all items will have, and what will be specific to weapons, armor, etc
• Implement the classes and methods on the classes, but don't actually plug them into the game yet

[aPruner]

PR opened: #23

done in PR #23 but of course, there will much more work to do later with plugging these classes into the game itself