Fix stageManager start/stop to always work

stageManager has always been annoying, requiring calling it several times to kill slow-dying processes, etc. Fix.

New behavior is that stageManager start in fact waits for the process to exist, stageManager stop loops over the status for ~10s, and then switches to kill -9 only if necessary. stageManager stopdead should never be necessary. And stageManager restart does what you want.