add failing test for Stream.select() with "empty" values
fix Stream.select() with "empty" values
Merge remote-tracking branch 'upstream/master' into stream_select_empty_values

Conflicts:
	CHANGELOG.txt
stream.select(component=..): only regard last character of channel code if it longer than 2 characters (+test)
Merge pull request #637 from megies/stream_select_empty_values

Stream.select() with empty values