Add a check to make sure the correct predefined geometry is being used

[andyprata]

I've done this twice now and maybe it's my own carelessness, but ORAC allows me to run on a geostationary imager using incorrect prelsm_file and pregeo_file entries. For example, I just ran on SEVIRI 41.5 degrees E data using the SEVIRI 0 degrees predefined geometry and no errors or warnings were raised.

I suggest adding a simple check on which satellite/sensor is being used that raises an error if incorrect geometry files are specified in the driver file.

[simonrp84]

Thinking about it, maybe they user shouldn't have to supply the filenames at all. How about something where you just set ```

use_predef_geo=True
predef_dir=/whatever/

And ORAC figures out the filename. That would prevent this confusion.
I also think we should merge the LSM and GEO files, as I doubt anyone is using one but not the other.

Am happy to take a look at this, but can't promise it'll be any time in the near future!

[adamcpovey]

Thinking about it, maybe they user shouldn't have to supply the filenames at all. How about something where you just set

I had been hoping to take all of the path calculation out of ORAC. People might want to put files in multiple folders rather than one, or have multiple versions of a file in the same location. And it's harder to explain "have a file called X" rather than "get a file that does Y and tell the program where it is".

However, what you say is easy to do so I shan't stand in the way.