The -i option can be used to set the source by index, whereas the -I
option can be used to set the source by name for the OpenHome product service
of a UPnP renderer.
This is handy to enable/disable the Songcast Sender or any other
external source, e.g. use scctl -I <device name> PL-to-Songcast to enable the
Songcast Sender Service.
Signed-off-by: Jörg Krause joerg.krause@embedded.rocks
