background_gradient vmin and vmax
Working with the new style API, I would like to turn several columns of a dataframe into something like a heatmap. I would like to use the same range for all columns in the subset, i.e., the colour map should take a minimum and maximum value I specify, regardless of what actual range each column has. Currently using the "min" and "max" this is not intuitive. I would much prefer to be able to specify explicit vmin and vmax values, analogous to the seaborn.heatmap function.

Thanks for the style API, extremely useful.
