[v1.0.2] - State Improvements

Posted a new version that addresses a few things. I deleted Rest and now we're using just Think. I also overhauled the Attack state because it was giving up too much control to the _unit. It now retains full control and performs regular checks to see if it should terminate early when the unit dies. Bunch of other minor improvements and comments. 

I also added a link to a private video (top of main.gd) where I do a full code review walk-through which should help give people a jump start on understanding it.