Android: Remove the _DW_EVENT_THREADING experiment. While it was more simple to launch a new thread to handle each event, this approach had numerous drawbacks. No reasonable way to limit the number of threads or memory consumed. Order of operations problems, the thread scheduler would control the order in which the events were handled, not the order of events produced by the UI. The non-threaded version has been working and stable for a while now even though it is more complicated for us to maintain our own event queue... this allows us to make sure the events are handled in order and we can limit the number of events in tight system resource situations.