graft() function will join multiple atctree objects together (internally this required structural alterations so that every atctree contains the root node)
subsetting ([) method now shows descendents of ancestor when j>0, and does nothing when j=0. (Previously it showed the direct lineage only when j>0, which wasn't very informative).
more examples, and all rewritten with pipe operator for clarity
fixed error in return from cutting() method
used internally: new helper atctree methods intree() and parents(), coercion of atctree to data.frame
minor alteration to layout of levels in plots
new slot drugnames for atctree class
look() atctree method finds nodes with a search term
show() method displays root node as well