Add weapon toggle inputs to InputManager.

New inputmanager methods:
TogglePrimary: check if Q was tapped
ToggleSecondary: check if E was tapped
NumKey: return int corresponding to pressed numkey, or -1 if none pressed
Merge pull request #31 from murphyslaw480/weapon-select-input

Add weapon toggle inputs to InputManager.
Merge pull request #32 from murphyslaw480/improved-unicorn

Improved unicorn
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
Add logo graphic to the README
Clarify git instructions in the README
Add new art assets.

Add new goblin and unicorn art.