0.9.0   This library contains external R functions to validate parameters of functions.
               The naming convention is that a function with suffix "N", e.g. AddExistN(),
               is categorized as a multi-validation function, as opposed to a single
               -validation function, e.g. AddExists(). Todo: Functions to validate parameters
               that are TWO(2)-dimensions, e.g. a data frame (dfr, zoo, xts) and a matrix.