Improve duplication of dynamics with 'Explode' feature

[oktophonie]

Exploding a two-note chord (one voice) with a dynamic will duplicate the dynamic (the voice assignment of the dynamic does not matter):

Exploding two voices with a dynamic does not:

It would be better if they were duplicated.

• A dynamic assigned to 'All voices' will go to all exploded staves
• A dynamic assigned to a specific voice should go to all staves containing notes from that voice
• In a case where there are multiple voices being exploded to multiple staves, dynamics assigned to specific voices should follow notes of their respective voices