Snap 1.0 released

After a long drought of activity on the snap crate, I've finally had time to put out a 1.0 release. I've also put up release binaries for the szip command line tool. (Like gzip, but for Snappy.)

In general, the API remains spiritually unchanged, but has had a facelift to be more consistent with the APIs of other compression oriented crates, such as flate2. Namely, previous uses of snap::Reader and snap::Writer should now use snap::read::FrameDecoder and snap::write::FrameEncoder, respectively. Also, thanks to the hard work of @emk, there is now also a snap::read::FrameEncoder, which reads from an uncompressed source and yields compressed bytes. (Kudos to his patience here. It took me almost two years to merge his PR!)

I've also removed all dependencies from snap and added hardware acceleration for computing checksums (when available).