Add type field to errors

This release adds an errortype field to thrown errors, allowing downstream consumers to respond differently to, for example, missing data versus a corrupt remote file.

v1.0.18

bump package version

v1.0.17

bump version in package.json

v1.0.16

export it

v1.0.15

untested file reader

v1.0.14

bump version

v1.0.13

bump version

v1.0.12

bump package version

Add two-bit reader

A new TwoBitReader class adds the ability to read sequence data in two bit format.