'override' auto-scrolling

Nobody has claimed this yet.

sure most has done this:
A track is playing
you want to inspect something in the track, perhaps it was just something you heard, or diddent :p
You mouse-grab the slider, and drag it, but to no avail
Auto-scroll forces the focus to be at play-head.
What i thought was that is would be reasonable that any manual drag of the slider, would indicate that user want to 'over-ride' the current view-position, and let the view change even if auto-scroll was on.

> When user then release the slider, the view would jump to auto-scroll pos. again.

NO i have done re-thinking on this. The reason the user want to move the view, is that he actually like to focus a _different_, than part, where the playhead is at _that_ moment. This fact makes this feature very simple to implement. The correct behavior is to simply **stop** playback, and then the user can freely scroll the view to any position of his choice. So the only thing that is needed is that user-scrolling of the view, should stop playback! Its as easy as that.

This feature should be for all editor-windows (curent lmms only have play-head-controlled scroll in P-R and S-E, but Automation-editor should hopefully soon(ish) be scrolling too)

Start by locating the play-head-controlled scrolling in the P-R and S-E editor windows, then check how the Automation-editor is expected to behave as scrolling is added there. Confirm the existing playback and view-scrolling interaction before defining the change; done means user-scrolling stops playback consistently in all editor windows that support this behavior.

Written by the indexing model from the issue text.