Clean up stand-alone I/O module

[mnlevy1981]

If you want to write a variable to netCDF, you should be able to specify one of many names (for example, "SqrBuoyancy", "SqrBuoyancyFreq", "SqrBuoyancyFreq_iface", "buoyancy_iface", etc) but those should all result in a variable with the same name ("SqrBuoyancyFreq"?) being made in the netCDF file. Similarly, you should be able to edit attributes using a wide range of names.

I think the best way to do this will be to create a simplify_name routine so that the multiple names only need to be handled in a single routine.