objarray : substraction

objarray substraction ?-sorted?<obj1> <obj2>

Return a new objarray removing from obj1 the items that are in obj2

<obj1> is the objarrays where <obj2> will be substracted.

if -sorted is set obj1 and obj2 are expected to be in ascending order (to avoid an extra effort to sort them)

The result is also an ordered array.