Auxiliary code for user interaction

Usage:ask_option_value(Description,Name,ValidValues,DefaultValue,PreviousValue,Value)

Ask (interactively) for a value for variable Name. Repeat until the user provides one of the ValidValues, or chose PreviousValue if none was provided.

• Call and exit should be compatible with:
  (basic_props:string/1)Description is a string (a list of character codes).
  (basic_props:atm/1)Name is an atom.
  (basic_props:list/2)ValidValues is a list of terms.
  (basic_props:term/1)DefaultValue is any term.
  (basic_props:term/1)PreviousValue is any term.
  (basic_props:term/1)Value is any term.
• The following properties should hold at call time:
  (term_typing:nonvar/1)Description is currently a term which is not a free variable.
  (term_typing:nonvar/1)Name is currently a term which is not a free variable.
  (term_typing:nonvar/1)ValidValues is currently a term which is not a free variable.
  (term_typing:nonvar/1)DefaultValue is currently a term which is not a free variable.
  (term_typing:nonvar/1)PreviousValue is currently a term which is not a free variable.
  (term_typing:var/1)Value is a free variable.