Adds lib

Fixes HPE_INVALID_HEADER_TOKEN

v2.6.0 (node-fetch#638)

* Update readme and changelog for `options.agent`
- Fix content-length issue introduced in v2.5.0
* More test coverage for `extractContentType`
* Slightly improve test performance
* `Response.url` should not return null
* Document `Headers.raw()` usage better
* 2.6.0

2.5.0 release (node-fetch#630)

* redirected property
* changelog update
* readme update
* 2.5.0

2.4.1 release (node-fetch#619)

* changelog update
* package.json update

2.4.0 release (node-fetch#616)

* changelog update
* package.json update

v2.3.0 (node-fetch#548)

* doc update
* handle corrupted location header during redirect

Fix import style to workaround node < 10 and webpack issues. (node-fe…

…tch#544)

* fix import rule for stream PassThrough

* avoid named export for compatibility below node 10

* compress flag should not overwrite accept encoding header

* doc update

* 2.2.1