Name: show_age - show the age of a living

Syntax:
	void show_age(int age)

Description:
	The show_age function writes a neat string containing the age of a
	living. If the age argument is provided (in heart_beats), it is used
	to calculate the age, else the real age of the living is shown.

Return value:
	None

Examples:
	this_player()->show_age();
	"12 days 8 hours 56 minutes 28 seconds."

See also: living/query_age