function [jLoops, jLoopObjs] = lick_getloops(hSys)
Checks for loops in system <hSys>. Only checks top level diagram, no loops passing subsystem borders are recognised. Returns an array list of loops <jLoops>, each represented by an array list of the object handles of those objects making up the loop in signal flow order. If 2nd left hand argument <jLoopObjs> is present it is a hashset of the handles of all objects found in any loop within <hSys>.