Close LineRecorder receiver's stream when closing LineRecorder

[dr0i]

This came up in metafacture/metafacture-playground#25 (comment):

Processing a flux pipeline results in empty data when doing this e.g. with the metafacture-playground, while it works fine when processing it using standalone metafacture-core.
The cause is probably: if the JVM is stopped after processing the streams of the receivers are closed automatically, thus the data is output correctly, while an unstopped JVM (like with metafacture-playground) doesn't close all streams properly (in some cases). Here it is the LineRecorder which doesn't close its receiver.