* *: randomize testnextnethttp.go listen port
* service/test: prefer t.Setenv
* *: cleanup port pid files
* service: fix final parallelization bugs
* address review feedback
* pkg/proc: fix test on windows
* fix finding port file on TestIssue462
Detach did not work for processes we attach to via PID.
Linux: we were only detaching from the main thread, all threads are
detached independently
Windows: we must resume all threads before detaching.
macOS: still broken.
Updates #772
