Comma separated lists - Version 2 update

[AlistairNWard]

Allow multiple values to be given to a command as a list of values separated by commas. Ensure tools that expect comma separated lists (e.g. Wham), get the expected values. In particular, a list of files, or repeated use of an argument can be used in gkno to specify multiple files, but Wham requires that the files are concatenated into a comma separated list and this single value supplied on the command line.