Set default maxFreq to 25 kHz. Unset pylab.hold for the bump_plot residual.

Set default maxFreq to 25 kHz.  Unset pylab.hold for the bump_plot residual.

It's probably a better idea to set the maxFreq to the Nyquist freq by
default, but only time for a quick hack at the moment.  You'll have to
neck down maxFreq to 7-10 kHz for softer cantilevers (~< 40 pN/nm),
since otherwise you'll start picking up higher order modes.

The bump_plot fix was just because plotting a bunch of data is _slow_.
Pylab in general is no speed demon, so the less extra work I give it,
the better.