R5:6fa25e4097aa

Makes extension usable with configured alternative file domain

Summary:
- adds library map
- updates readme to
-- use specific draw.io version
-- install extension in another dir than phorge (because that is the cleaner approach)
- reworks the js/css
-- use celerity to load the files from the alternative file domain
-- use javelin behavior to load the diagram data (loadJsExtension route is not needed anymore)
-- adds the toolbar button js/css with javascript from the phorge parent window
- with the last…