Remove GeoTrellis Types With Analogous Maml Types

[jbouffard]

Currently, we use GeoTrellis types in certain operations in Maml (mainly in masking). However, these should be removed and replaced with the corresponding Maml types. This has already been done for Neighborhoods and should be applied to the remaining GeoTrellis instances. These being: Extent, Point, Polygon, and MultiPolygon among others.

In addition to these new types, converters should also be made so that a Maml type can be converted to a GeoTrellis type and vice-versa.