Provide facility for user to input arbitrary regex, and name sheets in Excel output

This release addresses the two issues in the 2.1 Milestone.

This release inadvertently omitted some code that was intended to be included, and which was used in building the exe originally included in this release. This release is superseded by v2.1.1.

The input CSV file now has regex and excel_sheet_name columns. This allows users to give an arbitrary regex for descriptions where the autobuilt regex based on labels in the Discovery description won't work or is not what is wanted. If a regex is supplied, any label list also given will be ignored. excel_sheet_names allows specific names for Excel worksheets to be given where Excel output has been chosen (if output will be CSV, any sheet names given will be ignored). Note that characters known not to be permitted in sheet names will be removed, and that there is a hard limit on sheet name length of 30 characters, any sheet names supplied that are longer than that will be truncated. Names must also be unique within a workbook, any non-unique name will have n appended (or in the event of names at the 30 character limit naming will revert to Sheetn) - where n is the number of sheets in the workbook (including the current sheet). If three attempts to produce a unique name fail, the script will terminate with an error.