Allow different transposing instruments on one staff

Started a new thread in accordance with Marc's request here: https://musescore.org/en/node/110741#comment-750166

In compressed scores it is not uncommon for instruments in different keys to show on the same staff at the same time. Examples of this include Oboe and English Horn also E-flat Alto and B-flat Tenor Saxes. These are far more common in Concert Band music.

Along with this, I have seen scores that have two bassoons for example on one staff. Bassoon 1 is playing in the tenor clef while bassoon 2 is playing in the bass clef. I have seen it with other instruments such as horns also.