Fix typos in GameIndex
Use GameStores and State to update GameEcosystemGrid (fixes #2)

We were generating state from props and updating state on the change of
props, which defeats the point of having state and props and Stores.
Instead, the EcosystemGrid now:
 - gets initial state from the GameStores
 - watches the GameStores for changes
 - updates itself when the GameStores change