Cannot parse 'Avg' or 'Sum' files

[padraic-shafer]

BCS allows the user to repeat a scan and optionally store the average and/or sum of the scans, each in a separate additional file. The corresponding output file ends with "-Avg" or "-Sum"; i.e., text in the field. It is believed that this functionality is limited to the Single Motor Scan (*).

This currently crashes the ingest.get_data_file_header(), which expects the to be an integer. Allowing this field to be a string would enable the summary files to be read.

(*) For now, we'll assume that if this applies to the "From File" family of scans, then there should only be only one output file generated by each input file. I.e. the "file" keyword must not appear in the scan input file.

[padraic-shafer]

Created branch feature/0005/avg-sum-files.