- Move functions to modify input files to 'update_input_files.R'
- Move get_os, run_os, find_swat_exe, to 'utils.R'

- Implement useful functionality from run_verify
  e.g. start_date, end_date, years_skip
- Include check functions for function arguments
- Include set_print_prt and set_time_sim
- Update set_print_prt to consider wb_sft case
  which needs basin_wb_aa output to be written

- Tested current state of softcal routine