Item Inventory Support

[ethanmoffat]

Support item inventory management. Remove old code and item handling.

This is going to be a larger project since the old code for items touches a lot of different areas. Potential ToDo list for items:

1. Convert old EOLib.Net.API.Item code (and PacketAPICallbackManager) to new controller/action paradigm across EOLib and EndlessClient
2. Create new Inventory Panel (EOLib.HUD.Panels.InventoryPanel) based on old code (see Old directory in Panels)
   a. This will involve creating inventory items, item management control, handling drop/junk, etc.
   b. Do not need to support equipping or using items in this section
3. New panel should automatically be hooked up since it is already used in HudPanelFactory

[ethanmoffat]

This was split into #138 and #139