wkb:

Remove ambiguity between XYZ and XYM geometries when loading Point
GeoJSON from WKB. See comment in the diff for more details.
tests/wkb_test:

Updated XYM case of loading a Point from WKB.
tests/wkb_test:

Formatting.
tests/wkb_test:

Implemented the `test_dumps_linestring_z` case.