Geostructures

Fixes a bug in GeoPoint.from_wkt where negative values were not permitted

Features:
* Ellipse bounds are now exact
* Adds a new buffer_dt method to all shapes
* Hashers' hash_collection method now allows custom aggregation functions, but defaults to count (the previous behavior)

Changes:
* Renames vertices to edges

Bug Fixes:
* Fixes warning thrown by convex_hull property on collections
* Fixes issue with geopandas import/export
* Fixes bug where miniscule shapes would cause the NiemeyerHasher to return no geohashes

Overhauls to_shapefile and from_shapefile to use ZipFile
Adds a new method `strip_dt` to create a copy of a shape without its time bounds
H3 hexes drawn using plotly will now display their centerpoints on hover

* Delineates intersection and containment methods along different axes
* Optimizes shape instantiation time
* Partially resolves a float type inconsistency

Implements the following:
* Caches expensive methods and properties
* Changes the dt property to convert datetimes into zero-second time intervals (transparent)

Implements features:
* Filter shape collections by intersecting shapes, intersecting time dimensions
* Shapes now can test time intersection
* Adds the `bounds` property to shapes and collections
* Implements area and volume calculations on shapes