Progress::Any is an interface for applications that want to display progress to
users. It decouples progress updating and output, rather similar to how Log::Any
decouples log producers and consumers (output). The API is also rather similar
to Log::Any, except Adapter is called Output and category is called task.

Progress::Any records position/target and calculates elapsed time, estimated
remaining time, and percentage of completion. One or more output modules
(Progress::Any::Output::*) display this information.