[Denemo-devel] Fix for updating status after various changes.

[Richard Shann]

I've checked in fixes for setting the changed status after inserting
clef etc changes. This also fixed a latent bug in inserting barlines (if
they weren't working before they may be now).
These changed status updates are important for the LilyPond text window
to update, not doing so is perilous, since it has pointers back into the
DenemoScore for inserting LilyPond.
Richard