Routine Name:	input

Description:	Obtains input from the user at the GENESIS prompt.

Usage:		value = input [ prompt-string [ default-value]  ]

		value		value entered by user

		prompt-string	string to use to prompt user for input
				(default: "?"; to use a string that includes
				spaces, include the string in quotation marks;
				in any case, two blank spaces are always
				automatically shown after the prompt string)

		default-value	value to use if user responds by just pressing
				the RETURN key (to use a string that includes
				spaces, include the string in quotation marks)

Example:	genesis >  int x = {input "Value for x:" 3}
		(def = 3) Value for x:  666
		genesis >  echo { x }
		666

Notes:		The input routine can be used to get input from the keyboard.
		If supplied, the default-value is displayed before the
		prompt-string, in the form:
		
		    (def = <default-value>) prompt-string


