Adds .editorconfig
Refines support for programmatic agent activation

- Cleans up code so that it looks more consistent
- Switches `agent.start()` parameters to an object so users can
  understand more easily what's is being passed through.
- Improves example in README as well as in script
- Removes env variables for configuring agent settings. They are not
  needed anymore as the agent has a formal API now. This change makes
  the module much more friendly to use under different circumstances
  such as inside applications that are already using SIGUSR2 for other
  purposes.
- Fixes README according to new changes.
- The agent does not longer catch uncaught exceptions as it is up to the
  application using the module to do that.