rectify method will not chose 3rd polynomial even if there are more than 10 points

[timwaters]

This is a bug in gdal, we could count points and set this ourselves though?

https://github.com/OSGeo/gdal/blob/master/gdal/alg/gdal_crs.c#L209

Note the comment: /for now we avoid 3rd order since it is unstable/

So we should expect 3rd polynomials to be used, but by default they won't be