Release v2.0.1

Release notes:

2.0 is a relatively substantial new release, with new functionality, some small changes to existing user API, and some bugfixes:

• Added "view" parameters (paramnb.view.HTML and paramnb.view.Image) to link widgets to an output/display region.
• Added widgets for Date, Range and Color parameters
• Dict, Tuple, and List parameters can now be edited (with the results evaluated using ast.literal_eval)
• Widgets display evaluation and validation errors as yellow and red borders respectively
• Added continuous_update parameter to control whether callbacks are executed as sliders are dragged.

Backwards compatibility:

• The callback is now supplied the latest changed parameters and values as keywords
• Button callback now passes the parameterized instance/class to the callback
• continuous_update is False by default to avoid queuing up multiple callbacks during slider drags, in case the callbacks take time to run. You can restore the old behavior by setting continuous_update=True.