Konsole

* Add support for `volume` argument to `config()` as convenient alternative to
`level` argument for command line tools.

* After converting arbitrary detail values to strings, also split them into
lines.
* Ensure that type annotations are treated as strings, so that generic types
do not trip up konsole in Python 3.7 or 3.8.

* Fix `__all__` to list only symbols that actually exist.

* Use custom logging handler to make output redirectable with `contextlib`'s
`redirect_stderr`.
* Remove the now superfluous `konsole.redirect()`.

* Fix unexpected exception upon detail being an empty dictionary.
* More generally, improve handling of detail values that are effectively empty.
* Fix indentation of first line of exception trace.
* Add screenshot illustrating konsole's output to [project readme](README.md)

* Initialize konsole eagerly on first import. Replace `init()` with `config()`.
* Instead of replacing logging configuration with `basicConfig()`, augment
current configuration by adding handler to root logger and by replacing
logger class with subclass.
* Remove runtime dependencies on the standard library's `collections.abc`,
`dataclasses`, and `textwrap` packages to reduce import latency and memory
overhead.
* Completely refactor test script, improve coverage.
* Update documentation accordingly.