Interpolation fails with spectrogram

[jbfaden]

Can't find the ticket now, but there are often cases where one or two channels of a spectrogram don't interpolate, as if there's a linear bin width guessed and the data is log spaced.

Here is a similar ticket: https://sourceforge.net/p/autoplot/bugs/1012/

[jbfaden]

I tried unsuccessfully to demo this bug with a Jython dataset. This needs more work:

https://github.com/autoplot/dev/blob/master/bugs/ghdas/0125/demoBug125.jy