add more HTTPS links. IITC is likely still broken for HTTPS Intel Map.
serve own leaflet until they can make it available via https
Due to ingress.com/intel now force-redirecting to the HTTPS version,
loading dependencies just got a lot harder. External JS and CSS files
are now included directly in the file while building. This does not yet
work for plugins. I will make an emergency release soon, so at least
main works.
Use io.open to support python 2.x _and_ python 3