write_prompt - called when the parser wants a prompt to be written.

void write_prompt();

If write_prompt is present in the player object, the driver will call it
whenever the default prompt would normally be printed.  The driver will
not call write_prompt when the player is in input_to or ed.

 Tim Hollebeek  Beek@ZorkMUD, Lima Bean, IdeaExchange, and elsewhere
