#324 #334 optional process management

[joepio]

Makes all process management features opt-in. Makes the binary smaller, and has a more unix-like default behaviour.

PR Checklist:

• Link to related issue closes better to fail startup than auto-kill other running instances #324 closes distinguish start-the-service from service-specific tools #334
• Add changelog entry linking to issue
• Added tests (if needed)
• (If new feature) added in description / readme