Part- and phrasewise views of score #150

- Make types polymorphic
Part- and phrasewise views of score #150

- Make types polymorphic
Reimplement Score.Dynamics #82

Adds more HasDynamic instances
Reimplement Score.Dynamics #82

Removes unnecessary contraint on extracted (and HasPhrases (Score) ... instances)
This prevented composition of polymorphic phrase traversals