Multi-boundary method

[johnlees]

This implements the 'enhanced PopPUNK' method by Bin and Daniel.

TODO:

• [x] Make cluster output at multiple valid boundary positions
• [x] Apply the cluster QC method (in a script)
• [x] Calculate ANI (using sketchlib)
• [x] Hierarchical tree
• [x] Update docs with a new page on how to run all this
• [x] Add to tests