Message::text(): Omit parts with non-empty 'interface' key value
Message::text(): Omit parts with non-empty 'interface' key value

The specification says that parts with a specified, but unsupported
interface should be ignored. This is needed to let a CM to specify
a preferred text/plain alternative for a specially-formatted text,
such as quotes.

TelepathyIM/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyQt/telepathy-qt,TelepathyIM/telepathy-qt,TelepathyIM/telepathy-qt