* Update the SequenceCluster man page to give a more complete
  description of visualization code.
* Decide whether to convert "heat" to a generic function called
  "heatmap".
* Design and implement a reasonable interface to cluster and plot an
  alignment of the different consensus sequences.
* Design and implement a reasonable interface to add different labels
  (such as individual consensus sequences) to the "unrooted" phylo plots.
* Update the man page for `exportSG` to describe what it exports more
  completely.
* Figure out how the breakpoint data should be structured so we can
  find the chromomse names more simply.
* Enhance the 'Breakpoints' class to produce circos plots of
  translocations (with the virus).

