Pressure profiles

[jhod0]

Added Battaglia cluster pressure profile, projected pressure profile, and projected Compton-y parameter predictions.

Possible questions:

• Should the new interfaces be changed?
• Is the way I am handling h appropriate? The input radii need units of Mpc h^{-2/3}, and the resulting pressure is M_{sun} Mpc^{-1} s^{-2} h^{8/3}. Those are both a little awkward.
• Should I add other profile models before merge? (e.g. Arnaud 2012's model, Hill 2018's modified Battaglia profiles)