Fix and factorize Faust.delete().

It failed at execution because 'this' wasn't defined (F is the current object ref name).
By the way, we can just rely on FaustCore object to delete the handle.

wrapper/matlab/Faust.m

@@ -92,11 +92,7 @@ classdef Faust
 			% delete(F)
 			%
 			% See also Faust
-			if (this.isRealFlag)	
-				mexFaustReal('delete', F.matrix.objectHandle);
-			else
-				mexFaustCplx('delete', F.matrix.objectHandle);
-			end
+			delete(F.matrix)
 		end