Move most of replay code from FlxG and FlxGame to FlxReplay.

I just moved all replay code from one place to another. It compiles, but it's not working. The VCR code was slightly modified, but it remains in place.
Unbelievably it's recording and playing replays :D

The code is a mess with hacks everywhere, but I was able to save a replay session, load and play it. Best of all, it WORKED! HA! The VRC UI is not updating, I didn't test pausing/resuming/stopping the replay.