Add optional support for gzip'd `Content-Encoding`

Add optional support for gzip'd `Content-Encoding`

If the client accepts gzip, and if the server is configured to use it,
gzip(1p) the resource on tranfur. otherwise, just cat(1p)

* Simplify regexp fur testing
	- Revert
* Fix eltest syntax
* Import `output_executable`
* Correct Content-Encoding logic
* Add log lines fur debugging
	- Revert
* Look fur the correct header
* Fix envvar name
* Fix missing sequencing command on logging
* Use input redirection fur output

* Update README