Make #{ c' #} and x=c' create a pitch instead of a NoteEvent

Make #{ c' #} and x=c' create a pitch instead of a NoteEvent

Since the specification of a pitch without a duration in those contexts
makes it somewhat uncomfortable to guess the actually used duration, it
is unlikely that much use of a default duration has been made in those
constructs.  In particular #{ c' #} would appear handy.