Added replay frame timing with a canvas seeker and graph.

Fixes #497
I used
```
var commandManager = wtf.events.getCommandManager();
commandManager.registerSimpleCommand(...)
```
with
```
commandManager.execute('goto_replay_frame', this, null, frameHit);
```

to signal an update from ReplayFramePainter when a frame is clicked on. The shared command manager is created in ``MainDisplay``, which does not exist in the simple graphics replay view.

Would there be a better way to do this? Painters can't emit events, and passing the RangeSeeker to the painter seems to go against the patterns used elsewhere.

I'm also missing a ``wtf.events.CommandManager.setShared(null);`` in ``disposeInternal`` here, since I wasn't sure how that would interact with ``MainDisplay``.