- initialize hexes without a landtype assignment
- load landtype disktree
- update tests to match HIP-103 chart with all 3 data sets

HexAssignemnts wrap and labels Assignments. The order Assignments are
considered is not always clear unless you have HIP-103 up next to the
code. So we try to funnel all uses of the fields together into one
place, and callers deal with Assignments as a collection.

This is an attempt to simplify the trait soup hex boosting was starting
to become. Until there is a concrete need for more traits, I believe
this flow is easier to follow, and easier to mock at the level desired
in tests.

This command makes sure all values in a disktree file can be turned into
Assignment.

Now a geofence can be constructed directly without needing to go through
a file if you have a HexTreeSet.

The tables in HIP-103 list the assignments (AAA, ABC, etc,.) in the
order (footfall, landtype, urbanized). Having the Debug repr of
Assignments print in the same order makes it easier to cross reference
with the tables.

This test will break if the logic for deriving scores changes. If the
break is on purpose, the test should be updated.

This forces us to go through the proto enum, but provides a stronger
contract for going between types. very nice