Improved:
* Added -A/--aggregate-below-minimum option to the TSSV tool. This will
  add a line with 'Other sequences' to the output summing all sequences
  that were not reported because they had less reads than was specified
  with the -a/--minimum option.
* Clarified the help text for the -D/--dir option of the TSSV tool.

Fixed:
* Updated all tools to consistently handle cases where 'No data' or
  'Other sequences' occurs in place of a sequence.