Version 0.7.3

This is a minor release focusing on greatly improving the .interactive() API for flexibly building simple apps using widget controls. Thanks to @jbednar and @jlstevens for a few small fixes and many thanks to @philippjfr for all the rest!

Features:

• Improved .interactive Dataframe support: max_rows display, column access (#640)
• Improved accessor and attribute behavior for .interactive (#633, #635, #641, #642)
• Add .holoviews() terminal method to .interactive pipelines
• Add support for kwargs to .interactive.layout
• Misc fixes to .interactive API (#630, #632)
• Allow dynspread=True to be used with rasterize=True (now that Datashader supports it)