amended docstring.
refactored component initialization/cleanup.
Bump to 0.2.0-SNAPSHOT.
refactored analysis; added ':component/...' fields.
startup/shutdown only if not already running/running.
added 'peripheral.component/restart'.
redesigned 'defsystem' to allow for arbitrary data and subsystems.

This makes the `Subsystem` protocol obsolete, as well as the former
configuration design.
reset dependency components after stop.
added system tests.
adjusted API.