Test with branching

Trying my hand on branching
Revert "Test with branching"

This reverts commit 9c14122a7687cd398f8d0ba7960bd0b7c139e08a.
Rectified Priestly Taylor method for calculating PET

corrected Priestly Taylor method for calculating potential
evapotranspiration. This is the first edit. Future commits will try to
include documentation.
Minor changes

minor updates to radiation and soil moisture components