April Beta Revision 1

This release brings many improvements to April, including fixes to the printing function, the partitioned enclose function and the exposure of ⎕-prefixed system variables within the language. A (demo) option has also been added, making it possible to print a series of language demos. Finally, the (april-p) macro is now implemented alongside the standard (april). Using (april-p) causes the output of evaluated code to be printed in APL style by default.