You can place a thing into a stack now!

TODO:
1. Make hand unselect Thing after putting it into a stack
2. Display Things in Stack
3. Movement
4. Combat
I'm pretty sure that the movement logic is all there, just have to add
some logic to the HexButton Class and EndButton

We can definitly finish movement by the demo, maybe not combat.

It's 2:50 I'm tired going to bed, text me if you're coming in the
morning.