Update to version 0.13.0

Version 0.13.0 has been released. I thought it would be interesting to see what adding the ability to edit the villain's battle script would feel like. There's rough spots with the implementation, but it more or less works. 

This version almost certainly breaks saves from older versions. The "Clear Unlocks" button in the Preferences screen is mostly for debugging, but I'm leaving it in for now.

Added: 

- Ability to edit the villain's battle script can be unlocked

- Two more robots added

- "Clear Unlocks" button in the Preferences screen.

Changed: 

- Rewrote large parts of the battle system to support hot swapping pieces of the battle script

Fixed:

- "Get Magic" choice was consuming more time than it should have

- button image file was missing for some menus