tweak: initialise with existing environment

closes #50

Set environment variables on sub-process (#49)

* test: fix changed process execution

* test: upgrade phpunit

* test: implement mess detector and code sniffer

* ci: upgrade ci workflows

* ci: use pcntl

* ci: php 8.1 compatibility

* feature: set environment variables
closes #239

* test: assert multiple environment variables can be set

Improve code quality (#16)

* Improve code quality

* Initialise array

Merge pull request #12 from PhpGt/subprocess

Add LICENCE

Merge pull request #12 from PhpGt/subprocess

Add LICENCE

Merge pull request #9 from PhpGt/subprocess

Allow execution in subprocess

Merge remote-tracking branch 'origin/master'

Unset lines with no content

Test execution failure (missing command)

Merge pull request #3 from /pull/2

Pull/2