Create MonophylySimple_Clean.R

First monophyly assessor using mrca and descendants to determine genus-level monophyly.
Input: phylogenetic tree with tip labels in the format "genus_speciesepithet".
Output: matrix with rows "Taxa" containing all present genera, "monophyly" stating 'yes', 'no' or 'singleton' and "delta" indicating the difference between taxa of the genus and descendants of the mrca.