logical (bi-exponetial) scale support?

Any thoughts on adding logical (eg bi-exponetial) scale support?

Here's an example:
.

It would probably require a custom scale function for matplot lib (like [this](http://matplotlib.org/examples/api/custom_scale_example.html)).

Here is the reference for the "logical" scaling equation: [http://doi.org/10.1002/cyto.a.20258](http://doi.org/10.1002/cyto.a.20258).

I haven't really been able to find anyone who has done this in python yet.

Thanks for the library BTW!