cleanup, remove multi-arg support in 3d
add examples to README
start making Hilbert2d support multiple-axis-mode
simplify 3d rotations
simplify distance calculation in test
2d test tweak
make 3d hilbert into a class
2d rotation impl
add mod operator to Point
add top-level rotation support to Hilbert3d
update 2d test
add some command-line helpers

useful for quickly eyeballing / sanity-checking function values
properly invert top-level 3d
export more convenience methods
add axis-shuffling support to hilbert3d
add argument shorthands
tests for 3d mixed top-level pegging + shuffling
update README.md
bump to version 2