post a goal that will be executed when ECLiPSe is resumed.
	If no format argument is given, the goal is taken to be a string
	in ECLiPSe syntax. Note that (unlike with the C/C++
	interface) it is not possible to retrieve any variable
	bindings from ECLiPSe after successful execution of the
	goal.
	To pass information from ECLiPSe to Tcl, use queue streams
	as described later on. Example:
	
 ec_post_goal {go("hello",27)}
 
	If a format argument is provided, the ECLiPSe goal is
	constructed from goal data and format, according to
	the conversion rules explained in section 5.8. Example:
	
 ec_post_goal {go hello 27} (SI)
 
	Posting several goals is the same as posting the conjunction
	of these goals. Note that simple, deterministic goals can be
	executed independently of the posted goals using the 	ec_rpc command (see below).