Flag lyric changes so musicians can update chordpro

For Charts (and probably Planning), it would be incredibly helpful to have a flag when the imported lyrics have been updated, so that musicians are aware and can similarly update the lyrics in chordpro.

Otherwise the presented lyrics and the Charts lyrics are out of sync, which negates the benefit of having everything running on the same system.

I imagine this would be considerably simpler than the lyrics updating automatically in Chordpro, which may not always be desirable.