Add option for normalization

Based on the greatest distance from 0, this centers everything at 0.5, and is
useful for showing things that might be positive or negative.  Recommeded
colormaps include cm.RdBu, cm.PuOr, etc
Spin off binding data into BindUtils

This is in preparation for doing some very similar things from the PCA script
Code for doing WT-Zld-Bcd PCAs

See notes on September 23-24, 2014
make some basic attempt at not overfitting

what I've done here is split the data in half, then see how well
the two halves agree with each other
Tweaks for plotting on black background

Nothing to see here, move along!