Issue 4030: Lyrics associated to a Staff are placed on top of each other

Issue 4030: Lyrics associated to a Staff are placed on top of each other

The approach here is simply to avoid attaching to noteheads that have
actually started _before_ the current moment of time.  It is somewhat
irritating that includeGraceNotes cannot possibly be supported in
associated voices with its own timing (rather than the fully
synchronized \addlyrics or \lyricsto): Instead you need to use the same
durations, including \grace constructs, in order to match the note you
are aiming for.