Last commit before modifying NPK variable names.
parameter names refactored and code still providing the same results.
Changed name of state variables, code still running and providing the corrrect result.
Updated rate variables, code still producing correct results.
merged demand & uptake
integrated demand & uptake.
further modification of demand & uptake
Merged translocation routines.
cleaning up files after translocation changes.
Further cleaning up of NPK code.