POEx::Role::Streaming provides a common idiom for streaming data from
one filehandle to another.  It accomplishes this by making good use of
sysread and POE::Wheel::ReadWrite.  This Role errs on the side of
doing as many blocking reads of the "input_handle" as possible up
front (until the high water mark is hit on the Wheel).  If this
default isn't suitable for the consumer, simply override
"get_data_from_input_handle".  After Streamer has exhausted the
source, and flushed the last of the output, it will clean up after
itself by closing the wheel, the handles, and sending all of them out
of scope. If an exception happens, it will clean up after itself, and
let the DIE signal propagate.