Use higher-resolution climate and/or elevation rasters to extract environmental data for societies

[kirbykat]

Currently, the resolution of the rasters used is approx. 0.5 degrees. Once issue D-PLACE/dplace-dataset-ea#8 has been addressed, this would seem to me to be a priority, at least for ecological variables for which higher-resolution data are now available (e.g., historic temperature, historic rainfall, elevation, slope).