Commands to setup the file destination and format
- outdir [dir] Sets/gets the file output directory (string)
- fname [fn] Sets/gets the root of the output file name (string)
- index [i] Sets/gets the current file index (int)
- enablefwrite [i] Enables/disables file writing. 1 enables, 0 disables.
- overwrite [i] enables(1) /disables(0) file overwriting
- currentfname gets the filename for the data without index and extension
- fileformat gets the file format for data (no put?) What are the possible return values?