Dual land color selection could be better when color is obvious

**Is your feature request related to a problem? Please describe.**
When I'm paying for a spell (think Birds of Paradise - G) and I tap a Savannah, it prompts me for if I want to add W or add G. I very obviously want to add green. The selection could be made smart enough to know.

**Describe the solution you'd like**
When clicking on Savannah, G is produced (in this case).