Demo 1

Here we are, Demo 1.

I added a text interface for giving orders, and it's super clunky to be sure, but it makes the game fully playable.

```DemoPanel.java``` is just the GamePanel copied with the text interface added for giving orders. We aren't going to use this in the future, so I didn't want to mess up GamePanel.

The demo just runs two players, each with one tank, but of course any number of players and tanks could be added (this would just take forEVER to run through with the current text interface).

I also added little explosion effects for the bullets when they hit things.