implemented moisture model on grid instead of having an array of models, this resulted in a 5x speedup
added set_nearest_grid_point() for testing use only
cell_model.py is now only the reference implementation of the extended state moisture model
removed debug printing but added an ERROR output to log to indicate numerical problems
instead of T2, use 21.0 - T2 [deg C], removed printing of MAX TSM values/variances