Fix/reuse predictions

[adamwulf]

Fixes a number of issues, most of all how predicted points are handled.

1. a predicted point used to be associated with its estimationUpdateIndex. however, from the documentation this seems to be incorrect, and each predicted point should be handled on its own. all predicted points are appended to the path and only removed when a new concrete point has been added to the path. if other points are only updated, the predictions are maintained.
2. fixed an issue with the bezier stream incorrectly duplicating an element when it should only be reusing an element in its cache.
3. lots of tests added, including tests of streams of events, which are replayed with every possible split position
4. replaying events from the Example app will replay all remaining events in one batch starting from the existing endpoint, if possible
5. better re-render calculation for the Points view, taking into account the previous bounds of the path
6. added an event in the Example app to represent the callback from the gesture, so its easy to see which events were batched together
7. the antigrain smoother takes into account the indexes of the existing path, so that deleted elements can still be marked as having changed from the updated polyline delta
8. correctly update force/azimuth/altitude along with location in the Polyline
9. paths are allowed to be marked as complete, even if points are still expecting updates. this is because not all points will receive updates after the final .ended event has been sent