provide a batch mode to update the pdfs in a local dropbox

[bwl21]

Requirement

• Some improvements of Zupfnoter should be applied to all files in a local dropbox. It is cumbersome to open the same one by one in the browser.
• For regression testing it would be good to recreate files in batch mode

Solution approach

• use headless chrome and provide a command in url
• create a standalone script for node which works in the local dropbox

Actions

create a standalone script for node

• update to latest opal

• safely handle the different platforms

• refactor logger, controller etc. such that it can be used in both environments. In particular

  Logger <>- ConsoleLogger Logger <>- CLILogger