SCI: Notify scripts of completed fade when aborting it

This tweaks a fix/workaround (commit 96540686) for bugs #3266480 and #3041738.
Also add CHECKME to verify the accuracy of this workaround further.

This fixes the regressions #3291115, #3555404, #3596335 and #3610063.
SCI: Re-initialize more of MusicEntry on play

This fixes bug #3267956.