Add "Currently Shown" Module

[SenorPez]

There's no telemetry support for this, so it'd be a long (and probably ugly) hack to get this working. But if we could add a module that shows the current subject car of a replay, especially for "managed" replays where the viewed car is changed, that would be pretty sweet.

See BulletEyeDK's video for an example where this would be useful:
https://www.youtube.com/watch?v=nOix3K4Tv6E