Make the sequence borrowed instead of owned

Minor release that includes new no_strict=False parameter in sketch_file() Python binding.

This is a maintenance release updating dependencies and the minimum required Rust version (now 1.49). There are no functional changes in this release.

Changes:

• Better default distance calculation (support for the old calculation is available with --old-dist)
• Support for scaled sketches
• Adds a new, more compact binary format
• Improved Python bindings and pre-built wheels (note that Finch isn't on PyPI yet because of a naming conflict)
• Mash's distance calculation method has been dropped
• Improved testing and code QC

New features:

• Code cleanliness: cargo fmt, cargo clippyd (mostly), and bumped to Rust Edition 2018
• Support for sketches extensions of JSON in the CLI
• Preliminary Python bindings
• Support for numValidKmers in Mash binary format (note Mash itself doesn't support this, but will read from these files as long as they don't add a different field down the road: related issue marbl/Mash#112)

Fixes an issue with incomplete FASTQ parsing.

Fixes error parsing FASTQs with newlines at the end.

Update dependencies including needletail to v0.2.0. This allows finch to read bz, xz, and zip files (in addition to gz and uncompressed files) and allows "empty" records to be present (e.g. a FASTA file like ">test\n\n>newRecord").