Lmms: Off-grid automation points are not dragable.

[Sawuare]

To reproduce:

1. Open the automation editor.
2. Change the quantization value to 1/16.
3. Draw an automation point on the second step.
   
4. Change the quantization value to 1/8.
   
5. Try to drag the automation point.

It's not dragable and dragging it will create a new automation point.

[tresf]

Reminds me of https://github.com/LMMS/lmms/issues/391

[PhysSong]

I'm working on this. However, I need to choose the behavior for off-grid offsets. Should we preserve it, or not?

[Spekular]

Makes sense to preserve the offsets to me, as the same logic from the song/piano editors mostly applies and it increases consistency. If group move of automation points were implemented in the future it would make even more sense to retain off-grid offsets when moving an automation point at a coarser Q value.

[SecondFlight]

Agreed with @Spekular:

it increases consistency

Does holding down alt while dragging already allow you to offset automation points from the grid? I believe it does elsewhere and I think it would make sense to also do so here.

[PhysSong]

There are a lot of problems with off-grid automation points. To solve it, I need to rewrite the logic for dragging automation points.