[xcuActor] controller input buffering can get out of step

This issue was initially filed into JIRA by 'cloomis' at 17/Mar/16 2:38 PM as ICS-26.

Some XCU devices return line-delimited input, and the actor controllers consume input line-by-line. The current control flow expects the devices to be well behaved, and not to return extra or unexpected information. If extra lines are received they are buffered, and will be returned to later commands.

This is wrong, fragile, and dangerous.

There should always be a listener so that when a device blurts out junk or reboots the output is consumed and reported.

[ I usually do this correctly, but hoped that I could come up with a better implementation before the actor was finalized. ]