Remove perfectphyloR since it is no longer on CRAN (Fixes #17)

Phylogenetics.md

@@ -258,7 +258,6 @@ See the `r view("Epidemiology")` task view for details about packages useful for
 - `r pkg("aphylo")` implements a parsimonious evolutionary model to analyze and predict gene-functional annotations in phylogenetic trees.
 - `r pkg("CALANGO")` can be used to search for annotation terms (e.g., Pfam IDs, GO terms or superfamilies) associated with a quantitative/rank variable.
 - `r github("hr1912/TreeExp")` can be used to perform comparative analyses of gene expression in a phylogenetic context.
-- `r pkg("perfectphyloR")` can construct perfect phylogenies (a rooted binary tree that recursively partitions sequences) to provide insight into the pattern of ancestry of sequence data.
 - See the `r view("Omics")` task view for details about other useful packages.
 
 ### Gene tree--species tree and species delimitation