* bioaln: --gapstates implemented, but needs to add to POD & test
* biotree: deroot a tree
* biotree: --multi2bi; need to add to POD & test
* biotree: --bi2multi
* biotree: --cleanbr remove branch length; need to add to POD & test
* biotree: --cleanboot remove boot/node labels; need to add to POD & test
* biotree: --remove an OTU
* bioaln: -- add --informative
* biopop: bipart added; needs to add POD & test
* biotree: bipart (sister_pairs) added; needs to add POD & test
* biotree: swap-otus added; needs to add POD & test
