Pyviz

- Fixed InteractiveImage zooming to work with Bokeh 0.12.
- Added more responsive event throttling for DynamicImage; `throttle` parameter no longer needed and is now deprecated
- Fixed datashader-download-data command
- Improved non-geo Taxi example
- Temporarily disabled dashboard legends; will re-enable in future release

This release contains a major update to both the PyViz environment and the tutorial materials. The two main changes to the tutorial materials consisted of updating all the materials to replace the use of IPython magics with the new and now recommended HoloViews ``.opts`` API. Additionally all examples using the paramnb and parambokeh libraries have now been replaced with the new panel library which is much more capable.

The other major changes were to the dependencies which were updated to the latest versions of both the PyViz and PyData ecosystems. In particular there are major updates to HoloViews, GeoViews, hvPlot, and the addition of the newly published panel library.

Adds support for recent Panel versions. Still requires dev releases of some packages, so installation is from the pyviz dev channel.

As delivered at Strata San Jose, March 2018.

This release includes major contributions from jonmmease (raqgged array extension, SpatialPointsFrame, row-oriented line storage, dask trimesh support), jsignell (maintenance, website), and jbednar (Panel-based dashboard).

New features:

- Simplified [Panel](http://panel.pyviz.org)-based [dashboard](http://datashader.org/dashboard.html) using new Param features; now only 48 lines with fewer new concepts (707)
- Added pandas ExtensionArray and Dask support for storing homogeneous ragged arrays (687)
- Added SpatialPointsFrame and updated census, osm-1billion, and osm examples to use it (702, 706, 708)
- Expanded 8_Geography.ipynb to document other geo-related functions
- Added Dask support for trimesh rendering, though computing the mesh initially still requires vertices and simplicies to fit into memory (696)
- Add zero-copy rendering of row-oriented line coordinates, using a new axis argument (694)

Bugfixes and compatibility:

- Added lnglat_to_meters to geo module; new code should import it from there (708)