Add a test that runs moisture and precipitation options

[trontrytel]

Basically run all the possible moisture and precipitation options as a test and check that:

• there are no NaNs
• the equilibrium and non-equilibrium runs give similar results
• mass is conserved with no precipitation
• ... - more ideas?

[slayoo]

• constant-in-time potential temperature profile
• single-maximum in liquid water profile at any time in simulation
• no supersaturation at t=0
• cloud base height