Added nopt package dependency - npm update required!
Added -v cmdline option to show node module load errors, which are otherwise hidden by default with only a summary shown
The code scans the flows that are to be started and checks all
of the necessary node types are registered; if not, it doesn't
start the flows.
An event is emitted when each node type is registered - allowing
the server to track when all of the 'missing' node types register
and then start the flows.
This is a step towards adding node-types without restarting.