Specify the simplification tolerance in the units of the native raster CRS

[pjhartzell]

The final step in footprint generation is simplification of the polygon. At this point in the process, the polygon is in WGS84 degrees, so we ask users to supply a simplification tolerance in degrees as well. That is a highly un-intuitive value. Is there a way to allow users to specify a tolerance in unit of the raster's native CRS? And run a conversion to degrees for them?

We could add a crs_units flag option to the simplify_polygon method (assuming #3 is resolved by passing options to all methods rather than self assignment at construction).

[pjhartzell]

This may be OBE. #16 adds the ability to specify a destination CRS other than WGS84. I'm thinking we should keep the unit for simplify_tolerance to be that of the destination CRS since that is the CRS in which the simplification occurs.

• Perhaps we could offer a convenience function that converts from meters to the required decimal degrees. This is a bit fraught since the conversion changes with latitude, so a naive implementation would only be valid at the equator.