sds dev

Now more robust handling of date inputs for stacit().
New source usgs_seamless() elevation from the US.
CGAZ_sql() now works with no arguments, and returns a general query useable by vapour_read_geometry() and friends.
Add rema() and rema_v2().

sds 0.0.1

Renamed from spatial.datasources.

spatial.datasources 0.0.0.9000

All data sources from dsn are now here.