Introduce a Signal class that allows connecting event sources (signals)
to event listeners (slots) without adding any boilerplate code usually
associated with the observer or listener design patterns.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
