Panic on wrong packet length

[anti-social]

If you pass to a decoder wrong packet, it fails with the following error:

thread 'tokio-runtime-worker' panicked at /home/alexk/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/raptorq-2.0.0/src/octets.rs:749:5:
assertion `left == right` failed
  left: 632
 right: 1400

I think either this moment should be described in documentation or decoder should return an error. I would prefer error if it is possible.

[anti-social]

I did a simple patch that fixes this panic and #173 . I could try to make a PR.

I believe it is much better to return an error instead of a panic.

[cberner]

I think a panic is appropriate. The RaptorQ algorithm does not detect corrupted packets, so its the callers responsibility to pass valid data. If you'd like to submit a PR to document that I'm happy to merge it