New states for A.I. tasks, Item drops too.

More updates!

• Added the states: "Pickup", and "Storage" to the Worker A.I.
• Added the function to drop items (and spawn a representation of said item in the world), upon dropping - these items add themselves to the new "Pickup" task queue. This can now be used (as seen in the video) for bonus minerals on excavation, and will be used for loot dropped from enemies/etc.
• Grid now tracks Items on tiles (multiple items can be assigned to tiles).
• Added the Inventory to the Core building and Workers, allowing Workers to pick items up - carry them in their inventory, and store them in the Core building's inventory.
• Adjusted Fog of War after playing more DK1, noticed that cavities don't fully reveal when you break into them (unless they are filled with water/other tiles), Fog is now revealed based on Units and their exploration (This will make the planned Scout unit actually useful).