Move in wr-replay

[kvark]

https://github.com/kvark/wr-replay
Could live in this repo as a binary.
Would increase the discover-ablitiy, make sure the code is up to date.
Related - #494

[kvark]

I've been messing with the move process and faced a few issues:

1. While I can preserve the source history, I don't think Cargo.toml one needs to be saved
2. Too bad the webrender is in a sub-dir of the crate, since the binary would need to be as far as webrender/src/bin/replay.rs now
3. Cargo doesn't support binary-only dependencies (Allow dependencies that only apply to specific cargo targets (bin, example, etc.) rust-lang/cargo#1982), and so it's unclear how to properly depend on glutin for this binary. One way is to make it an "example", but this doesn't sound good to me.