Made find_minmax robust to different input
Added table method to Layer
Fixed bug in IPython based widget
Fixed Bars now provides same API as Histogram
DataView now accepts Tables in constructor
Enabled plotting of Bars
Fixed dim_values on Raster types
Added appropriate dim_values for HeatMap
Points now accepts Table in constructor
Simplified conversion methods of Pandas DFrame interface

Conversion method on pandas and seaborn DataFrame wrapper
DFrame now much simpler but with support for conversion
of most existing View types.
Points dim_values now returns NaNs if no value specified

Allows consistent return types for constructing Table