Reorganize data.cljs

[tbeddy]

Even when using a more compact representation for maps (q, r, terrain-type on one line), adding all of the maps from Elite Command pushes data.cljs over 11k LoC, and it's only going to get longer. We should break it up into a few related files and break maps up further into map-packs.

[djwhitt]

I'm fine with splitting it up into different namespaces. In the long term, we should move most if not all of the data out of the code base and into separate data files (#40 is related).