Hilbert geohashing in Node.js

This repo is basically interoperable Node.JS port of https://github.com/tammoippen/geohash-hilbert/
Geohash a lng/lat coordinate using hilbert space filling curves.

To install: npm install hilbert-geohash (https://www.npmjs.com/package/hilbert-geohash)

Simple encode/decode:
``js
const { encode, decode } = require("hilbert-geohash");

encode(24, 61) // ZWSQ0WSQ0W

decode("ZWSQ0WSQ0W") // { lng: 24.000000078231096, lat: 60.99999996833503 }

`
---
Detailed usage:
`js
const { encode,
decode,
decode_exactly,
hilbert_curve,
neighbours,
rectangle } = require("hilbert-geohash");


// encode(lng, lat, precision = 10, bits_per_char = 6)
encode(24, 61) // ZWSQ0WSQ0W

// decode(lng, lat, bits_per_char = 6)
decode("ZWSQ0WSQ0W") // { lng: 24.000000078231096, lat: 60.99999996833503 }

// decode_exactly(lng, lat, bits_per_char = 6)
decode_exactly("ZWSQ0WSQ0W") // {
// lng: 24.000000078231096,
// lat: 60.99999996833503,
// lng_err: 1.6763806343078613e-7,
// lat_err: 8.381903171539307e-8
// }

// neighbours(geohash, bits_per_char = 6)
neighbours("ZWSQ0WSQ0W"); // {
// 'east': 'ZWSQ0WSQ0X',
// 'west': 'ZWSQ0WSQ0o',
// 'north': 'ZWSQ0WSQ0i',
// 'north-east': 'ZWSQ0WSQ0h',
// 'north-west': 'ZWSQ0WSQ0n',
// 'south': 'ZWSQ0WSQ0V',
// 'south-east': 'ZWSQ0WSQ0Y',
// 'south-west': 'ZWSQ0WSQ0p'
// }

// rectangle(geohash, bits_per_char = 6)
rectangle("ZWSQ0WSQ0W") // {
// "type":"Feature",
// "properties": {
// "code": "ZWSQ0WSQ0W",
// "lng": 24.000000078231096,
// "lat":60.99999996833503,
// "lng_err":1.6763806343078613e-7,
// "lat_err":8.381903171539307e-8,
// "bits_per_char":6
// },
// "bbox": [
// 23.999999910593033,
// 60.999999884516,
// 24.00000024586916,
// 61.000000052154064
// ],
// "geometry": {
// "type": "Polygon",
// "coordinates": [
// [
// [23.999999910593033,60.999999884516],
// [24.00000024586916,60.999999884516],
// [24.00000024586916,61.000000052154064],
// [23.999999910593033,61.000000052154064],
// [23.999999910593033,60.999999884516]
// ]
// ]
// }
// }

// hilbert_curve(precision, bits_per_char = 6)
hilbert_curve(1); // {
// "type":"Feature",
// "properties": {},
// "geometry": {
// "type":"LineString",
// "coordinates": [
// [-157.5,-78.75],
// .
// .
// .
// [157.5,-78.75]
// ]
// }
// }

``