datenumber – Convert a date into a number and vice versa

This pack­age pro­vides com­mands to con­vert a date into a num­ber and vice versa. Ad­di­tion­ally there are com­mands for in­cre­ment­ing and decre­ment­ing a date. Leap years and the Gre­go­rian cal­en­dar re­form are con­sid­ered.