Changed geonodelink plugin to accept a filename or vega spec object as an argument (in preparation for moving geonodelink.json).
Changed geodots to accept a string or object as a vegaspec parameter.
Moved geonodelink.json into examples directory.
Moved world data into examples directory alongside geonodelink JSON file.
Merge branch 'trim-repo'
Moved vtkweb functionality into separate class.

Closes #182.
Merge branch 'vtkweb-class'
Moved streaming API into its own class.
Replacing manual generation of random key with use of tangelo util function.
Merge branch 'streaming-class'

Closes #198.
Improving form of import statement.