colab notebooks, GlvisData class, update esm ref to releases-js

Merge pull request #44 from GLVis/anywidget

Rewrite to use anywidget

Merge pull request #32 from GLVis/release-0.3.3

0.3.3 release

0.3.2

0.3.1

0.3.0

v0.3.0

release 0.2.0 glvis & 0.1.0 glvis-jupyter