Extend the input_calendar SetPrompt to accept / convert all the available inputs and not only the commonly used.
For instance: when showing the prompt, the AM/PM is shown as %p instead of AM/PM.
The following list is not correctly shown on the Prompt:
%a abbreviated weekday name
%A full weekday name
%b abbreviated month name
%B full month name
%C century number
%j day of the year ( 000 .. 366 )
%n a newline character
%p "PM" or "AM"
%P "pm" or "am"
%U, %W, %V the week number5
%u the day of the week ( 1 .. 7, 1 = MON )
%w the day of the week ( 0 .. 6, 0 = SUN )