Re-Vamped weapon manager to inventory manager

I changed weaponmanger to inventory manager. I added an item.cs file
because that is the object I am using in inventory manager.

It is probably this will change but it takes out the weapon switching
making room for item switching/getting.

Let me know if there are problems.
Merge pull request #34 from kalgynirae/andrew-branch900000000

Re-Vamped weapon manager to inventory manager