Python-readiness

- Ignore invalid wheels instead of erroring
- Better support for environments or requirements with prerelease package versions
- Reduce padding in output
- Add graphing code

- Allow `--env` to resolve environment from a Python executable
- If we've printed partial progress, make sure to print complete progress to avoid confusion
- Print messages when determining default Python version or environment

- Use bisection by default. This finds earlier supporting versions, but means there may also be
intermediate versions satisfying the requirement without relevant support. You can use
`--monotonic-support` to regain that guarantee, if useful, using the old linear search.
Bisection is also significantly faster.
- Improve logic for handling yanked versions
- Use `Requires-Python` metadata to help determine support
- Add `--env` option to check a specific environment
- Show intermediate progress every 1 second
- Compress and version the cache, improve cache resiliency
- Add `--exclude-newer` option to exclude package versions newer than a given date
- Add a shorter timeout to HTTP requests
- Retry failed HTTP requests
- Fix support for Python 3.9
- Avoid checking installations originating from cwd
- Improve `--help` output

- Initial release