April Initial Beta

This is April's first full beta release, featuring 93 primitive functions and 14 operators. It can return the results of calculations in the form of native Lisp arrays as well as expressing arrays in the form of strings formatted in the traditional APL style. Outside of the APL implementation itself, several features are in place to make development with April faster and easier. These include the (april-p) macro that automatically prints APL-formatted output along with returned results and the (with-april-context) macro that allows a single set of parameters to be used for multiple invocations of April.