update changelog

update readme (#219)

release v0.23

Update First(n int) to read no more data than necessary (#199)

First(N) now closes its output after it has read N lines, terminating the pipe 
without consuming unnecessary further input (apart from the 4KiB scanner 
buffer).

Co-authored-by: John Arundel <john@bitfieldconsulting.com>

Refactor

Filter: preserve previous error if func succeeds

Report ExecForEach command exit errors to the pipe

short-circuit on error (fixes #141)

Tweaks

Merge pull request #139 from bitfield/http

Add HTTP support via Do, Get, Post