Promise-based write API?

[charlieforward9]

shp-write/src/write.js

Lines 15 to 16 in 48a0fe7

	// Low-level writing interface
	function write(rows, geometry_type, geometries, callback) {

While updating the README, I realized that write does not use async/await. This seems ancient. This issue tracks the upgrade of this (unless the current callback form is in fact better for some reason)