Cleaning
Cleaning
Renames Time and Duration to TimeT, DurationT
Renames Pos and Dur to Time and Duration
Cleaning
Changes Time and Duration kinds to (* -> *) -> *

This means we can make time and duration instances for Score, Voice, Part etc.
(We could even to it for lists, using Int). This simplifies combinator types
quite a lot: we no longer have to assert (Time (s a) ~ Time (s b)) etc.

On the other hand, Delayable, Stretchable et al gets more complicated type
signatures.
Simplifies HasEvents
Simplifies type of Transformable