Logarithmic color scale

[kpedro88]

In a two-dimensional histogram, the color scale represents the z axis. It would be useful to have an option to display this in a logarithmic scale, as can be done with the x and y axes when viewing data from a 1D histogram.

An example of where this could be used: https://www.hepdata.net/record/ins1749379?version=1&table=T1tttt%20cross%20section%20upper%20limits (the PNG shows a logarithmic z scale, but this is not currently viewable in the "Visualize" section).

It would also be useful to allow logarithmic views of the x and y axes in the Visualize section for a 2D histogram.