Changing from python 2 kernel to python 3 kernel does not reload map

[kotfic]

By default, example notebooks are saved with geonotebook2 kernel. If run from python 3 only geonotebook3 kernel is available. Notebooks are 2/3 compatible but switching the kernel triggers some kind of change-kernel event that we're not capturing with register_events in index.js. In any case the map does not load.