Tell FTSW500 desired output file location

[dc2917]

We can currently set the desired output path, filename and data description from our GUI. FTSW500 has similar functionality. We just need to tell FTSW500 our preference, which can be done using the already implemented set_output_path_prefix, set_output_prefix and set_data_description methods.

This should probably happen when we first connect to FTSW500, and whenever these fields are changed from within our GUI.

[alexdewar]

I've just been looking at this. Unfortunately, there's a bug in FTSW500 which means if you try to set the output path prefix to an absolute *nix path (i.e. starting with /) then you get an error message about the path being invalid. Presumably the fix on their end is to just use whatever the proper path handling functions are in Java rather than some open-coded hackery that only works on Windows. (In theory they're only targetting Windows, but that's still no excuse 😉.)

So let's put this on ice for now and see if we can get ABB to fix up FTSW500 for us.