IMOS filename check depends on command line arguments

[mhidas]

Currently the filename checker can only access the name of the netCDF file being checked by reading the command-line arguments directly. This is worked initially, but will need to be constantly updated to match the argument handling in the main code, which has indeed changed quite a lot since the filename checker was written.

The best approach would be to either find another way to access the filename (without modifying the core code), or to create a completely stand-alone module for the filename checks.