* Added `unpack` and `unpack_by_func` to `skbio.tree.TreeNode` to unpack one or multiple internal nodes. The "unpack" operation removes an internal node and regrafts its children to its parent while retaining the overall length.
* Added `support` to `skbio.tree.TreeNode` to return the support value of a node.
* Added `permdisp` to `skbio.stats.distance` to test for the homogeniety of groups. ([#1228](https://github.com/biocore/scikit-bio/issues/1228)).
* Added `pcoa_biplot` to `skbio.stats.ordination` to project descriptors into a PCoA plot.
* Fixed pandas to 0.22.0 due to this: https://github.com/pandas-dev/pandas/issues/20527
### Backward-incompatible changes [stable]
### Backward-incompatible changes [experimental]
### Performance enhancements
### Bug fixes
* Relaxing type checking in diversity calculations. ([#1583](https://github.com/biocore/scikit-bio/issues/1583)).