Cyclic color map

A constant-lightness cyclic colormap for phase.

Three functions are included here:
1. phasewrap easily wraps data to the range -180 to 180 or -pi to pi.
2. phasemap is a constant-lightness cyclic colormap developed by Kristen Thyng. The constant lightness is good for displaying phase because it does not put strong emphasis on any part of the color map. A well-written and aesthetically-pleasing overview of Kristen's cmocean colormaps can be found here: http://matplotlib.org/cmocean/
3. phasebar makes a circular colorbar.

The phasemap colormap is from the cmocean package, and we've written a peer-reviewed paper about cmocean which has just come out in the journal Oceanography. If these phasemap is useful for you, please consider citing our paper:

Thyng, K.M., C.A. Greene, R.D. Hetland, H.M. Zimmerle, and S.F. DiMarco. 2016. True colors of oceanography: Guidelines for effective and accurate colormap selection. Oceanography 29(3):9–13. http://dx.doi.org/10.5670/oceanog.2016.66