The QGeoSatelliteInfoSource signals should be merged

At present QGeoSatelliteInfoSource emits two signals - sattelitesInUseUpdated(QList<QGeoSatelliteInfo>) and satellitesInViewUpdated(QList<QGeoSatelliteInfo>).
This is fine for when clients want to keep track of one or the other (or, more likely, one and then the other).

If a client wants to keep track of both at the same time they will need to implement some complicated logic to keep the data coming from the two signals in sync. All implementations currently emit both signals at approximately the same time, although since we don't make any guarantees about that the clients need to handle a much more complicated case than they should.

An alternative has been proposed, where QGeoSatelliteInfo would have an bool inUse() and void setInUse(bool) methods and the signals would be merge to satellitesUpdated(QList<QGeoSatelliteInfo>).

This appears to be a superior solution to what we currently have, and would have made it into the 1.0 release if the suggestion had been brought up with time for us to make the change and test it properly.