Name: clear_screen - clear the screen of a player

Syntax:
	clear_screen(int flag)

Description:
	The clear_screen clears the screen of a player. If flag is not given,
	it only clears the screen of the player, if the term type is known.

Return value: 1

Examples:
	this_player()->clear_screen();

See also: helpdir/cls, helpdir/set, player/query_term