Moves the "file existence verification" step outside of loop that visits every reference in an org. This was causing the course digest to take several minutes to run when faced with a large course that has many organizations.
Simplifies the command line operation, supplying useful default to all but the inputDir. Now, to invoke the "convert" operation against a course, you can simply do:
npm run start -- --operation convert --inputDir /Users/darrensiegel/dev/courses/chemistry/chem1/trunk
This PR does two things: