allows to explicitly specify json as format
check that taxon_names are characters
use match.arg for file formats
minor typo
Merge branch 'master' of github.com:fmichonneau/rotl
updated .gitignore
check that node_ids or ott_ids are not NA
BSD 2-clause license in CRAN format
check NA only if ott_ids or node_ids are not NULL
Merge branch 'master' of github.com:fmichonneau/rotl
imports ape namespace
specify namespace for collapse.singles
Merge branch 'master' into testing