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 <[email protected]>

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

Change some t.Errors to t.Fatals

Don't close pipe in SetError (#120)

Fixes #117.

* The pipe shouldn't be closed on SetError function

* Fix TestExecRunsGoWithNoArgsAndGetsUsageMessagePlusErrorExitStatus2 test. It was not checking that exit status is two

* Update test name to match what is really doing

* Fix example for getting exit status from exec

* Add new example for exit status not zero on Exec

Merge pull request #106 from bitfield/jq

Add JQ filter