Partially fixed input weather data handling. Found a way to convert tifs to netcdf. Modified functions accordingly. Sequential optimisation of code well advanced, will try multiprocessing after.

Fixed equations, deleted some temporary variables to reduce memory usage, used eval() function to improve readability.

run_samir() operational. Outputs are not yet valid, updated dev_samir_xarray.ipynb for comparison with modspa excel and added validation inputs and outputs for comparison.