Extensions (#737)

- add the current document title in the toolbar
- allow user extensions to define optional parameters
- more events for renamedElement, beforeClear, afterClear, sourceChanged
- remove "message" event used for iframe integration not used anymore. can be readded through a new extension if necessary
- default precision down to 2 digits (and applied in rotation)

rollup.config.js

@@ -1,4 +1,3 @@
-/* eslint-disable node/no-unpublished-import */
 /* eslint-env node */
 // This rollup script is run by the command:
 // 'npm run build'