Support for karaoke effects

[occivink]

At the moment, karaoke'd lines are not properly handled. The lines generated all have the same karaoke markers as the original line, effectively overriding the karaoke effect.

Ideally, they should be updated in a similar way to the \fade tag, with each marker being offset depending on the frame, to preserve the original karaoke effect.

[torque]

I'd (surprisingly?) never received a request for this before, but it shouldn't be too hard to add.

[torque]

Closing as fixed with the release of beta 4. Feel free to reopen if you have problems.

[occivink]

I greatly appreciate how promptly you worked on this and the fix works very well for \k and \ko tags, however it does not behave properly for \kf tags. Decrementing the duration does not offset the starting point, which is what you'd want. You can easily notice this if you have a line covered by a single \kf tag on which you apply tracking data.

From what I've seen, instead of decrementing the tag value by the offset, adding an additional \kf tag before with the negative offset gives the intended behaviour. For example this
{\kf56} => {\kf52}
doesn't work, but
{\kf56} => {\kf-4\kf56}
does.

Another small issue is that when a tag gets decremented to 0, it leaves trailing empty braces. However, this is easily cleaned up.

Thank you for your work.

edit: I would reopen the issue, but I don't see how to. Should I report it as a new issue?

[torque]

Shifting \kf should be fixed as of 761cf4d. Thanks for the description of the behavior and solution.

Also added removal of empty braces in 7cc6f97.

Re: reopening the issue, there is a "Reopen and comment" button for me, but maybe that's because I'm the owner of the repository.

[occivink]

This works nicely, thank you very much!