Treat Continuous lines as Karaoke Syllables when moving boundaries.

[TechNiko]

When moving the common boundary (on the Audio Display) between two lines that are continuous and selected, move that boundary for both lines. (Like Karaoke Syllable work)

[nielsm]

This shouldn't happen always, but only in some special cases, eg. when holding down a key. I'm not sure if I understood the request correctly, but with "and selected", did you mean "both lines are selected simultaneously"? If then, that might solve it nicely... I think.
Can you even use audio timing atm. when multiple lines are selected, and/or does it produce sensible results?

Also, how should this behave with respect to committing? It's obvious when using auto-commit, but what about when that's disabled? I don't think Aegisub can handle having two uncommitted lines as it is now. (And how should it be displayed in the UI?)

[TechNiko]

Yes I mean when both lines are selected simultaneously. Yes we can use Audio Timing when multiple lines are selected, it's a new feature, it sets all the selected lines to the new Audio Display area at once, which is great. Committing should work the same way as it does for multi-line timing does right now, I'm not aware of its inner-workings.

[ArchMageZeratuL]

IMO, this shouldn't need both lines to be selected, but should only work while holding down ctrl, shift or alt.

[nielsm]

I'll try to lump this into the audio display rewrite.

[verm]

Bump 2.2.0 tickets to milestone:3.0.0 (2.2.0 is becoming 3.0.0)

[plorkyeran]

(In [6460]) Modify the TimingController interface to support dragging more than one marker at once. Updates #20.

[plorkyeran]

(In [6461]) Support dragging multiple markers at once in the dialogue timing controller

When ctrl is held down and the user clicks on one of the active line's
markers, all markers at the same position as the clicked marker (for
both active and inactive lines) are now moved along with the clicked
marker.

Closes #20.