Update add_map_properties_to_start_of_grid_file to use the NexusFile architecture to do the updating #265
Description
Is your feature request related to a problem? Please describe.
Currently the add_map_properties_to_start_of_grid_file method directly overwrites the file which goes against the principles of -> modify in memory -> then user calls update simulator or write case to overwrite the file or write out a new case file.
Describe the solution you'd like
Use the modify NexusFile function calls like the constraints.modify style calls use.