choice for PianoRolls on import

[tjingboem]

Blue can import midi files.

It would be nice if user, on import, could choose between opening the midi file with PianoRolls or the present way, ie. opening in GenericObjects.

Since the PianoRolls opens in default in 12TET, the midi notes would fit right in- just like in other DAWs.
Further additions should be: beat detection, so the Use tempo is activated if the midifile provides the tempo.