* Disable warnings about HTML reports and standalone support.

* Include 'html_reports' in the set of stable features.

* Suppress html and csv if the feature flags are missing.

* Make the CSV dependency optional.

* Group optional dependencies in cargo manifest.

* Test both with all features and no features.

Some tools (e.g., rhysd/github-actions-benchmark) that parse the output of criterion do not correctly parse the standard output if it contains an unexpected string, such as an error message. The fix in this commit ensures that the tool will work correctly in environments where gnuplot is not installed (e.g., GitHub Actions runners).

Also, from the conventions of the command line interface, it is preferable that such error messages be output to stderr.

* Make the plotters dependency optional.

* Turn rayon into an optional dependency.

* Add cli flag for discarding baselines rather than saving them to disk.

* Disable plotting if html_reports is disabled.

* Support testing with and without the html_reports flag.

)

* Use terminal code to clear the line.

* Print status messages to stderr.
Status messages such as 'Warming up', 'Analyzing', etc.

* Use the 'anes' library for handling terminal escape codes.

* Accept subsecond durations from the command line.

* Replace 'to_nanos' with 'as_nanos'.
'as_nanos' stabilized in 1.33.

…505)

* Add --quiet flag. When enabled, only a single line is printed per benchmark.

* Print warnings and errors to stderr.

… not be found

* Enable --quick mode.

* Add basic user guide for the new 'quick mode'.

* Document WASM support with wasmer, wasmtime, nodejs, and browsers.

* Bump MSRV to 1.56 as required by ciborium

Clap v3 is a new major version of clap with several deprecations and
breaking changes, all of which are addressed within this commit.

* Delete critcmp code (it belongs in cargo-criterion)

* Bump MSRV to 1.57 due to os_str_bytes.

* Mention MSRV bump in CHANGELOG.