Added (1) building NJ trees, and (2) convert NJ trees (of class phylo) to class hclust by making them ultrametric
Added (1) building NJ trees, and (2) convert NJ trees (of class phylo) to class hclust by making them ultrametric

robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo,robertaboukhalil/ginkgo