Add some user-friendly / interactive features

[TrakJohnson]

• [x] custom chain input
• [ ] undo - should be easy, just store a list of the previous aminoCoordMap
• [x] randomizer instead of flat chain to make the game harder
• [x] make some preconfigured chains with stored best score - so that the user knows whether his config is the best

[Pyxidatol-C]

The custom input does the job of a randomizer.