The following changes are included:
- Delete per-file license notices at the top of each file.
- Delete the first paragraph of LICENSE-MIT (an inaccurate
pseudo-copyright line), leaving only the text of the MIT license.
Nothing about the license of Serde code has changed, only our
understanding of how to correctly communicate that license has changed.
This mirrors an equivalent change being applied in the rust-lang/rust
repository.
Since we know exactly how many bytes we should serialize as we can hint
to the serializer that it is not required which further reduces the
serialized size when compared to just serializing as bytes.
