Problem modifying colorbar properties after using custom LUT

[mwaskom]

Just noticed this in the docs I built after the colormap enhancements, sorry.

Turns out that in the probabilistic colormap example, modifying the number of hues and labels on the colorbar reverts the colormap from RdPu, which the code asks for, to Greys, which I chose as the default string to pass to the mlab functions (with the expectation that it would signify problems with the colormap choice by its lack of color).

I'll fix this, I'm just opening the issue because I can't get to it right now.

I actually don't think we're doing anything wrong here; we're using the approved way of specifying a custom colormap. So I think it might be a mayavi bug in communication between the colorbar and the colormap. But at the very least I'll fix the example.

[mwaskom]

I've fixed the example, but am still not sure how to avoid this behavior. However, it just breaks messing around with the mayavi backend, not anything in the PySurfer interface itself, so I'm not going to consider it blocking 0.5.