destroyAll triggered from the world object causes the instance counts and consequently all the subsequent uniqueStringIDs to re-start from scratch
added helper function "morphFromUniqueIDString"
adding capability for test recorder/player to record right mouse clicks not in terms of pixel coordinates but in terms of which morph ID to pop a context menu for. This should cater minor changes in setup of the world and will allow much easier editing of tests.
adding example test for seeing that right-clicks are now recorded in smarter way (see previous commit)