Configurable mouse playback control behavior, customizeable clicks bindings, and ability to shift/move subtitles using the waveforms interface

[nekohayo]

I have recently discovered the waveforms feature in the app and it is a little revolution. This makes everything so much easier, it's fantastic! It should be turned on by default in the UI and suggest generating the waveforms (#30) to highlight how essential this feature is.

However, there is no way to use it to shift or reorder subtitles, and I would like to be able to use some configurable mouse+keyboard combo to do this, because it's a bit annoying when there are long gaps in the dialog and you have to adjust both the in and out points of the new subtitle being added (short of having a "insert subtitle at playhead position" feature).

Furthermore, besides the simple "shifting" usecase, there's the "reordering" usecase. Imagine someone hands me a preliminary edit of a video to be subtitled, and then later on swaps the ordering of some scenes... I would want a way to be able to move subtitles around efficiently, ideally with a multiple selection of items and dragging them to "insert" them somewhere else (and have the other subtitles "ripple" to create space, then select the other ones and move them/realign them.

I also find myself fighting a bit with the default mouse behavior, which is:

• Left click = subtitle inpoint
• Middle click = move playback cursor / playhead (but it doesn't allow scrubbing, see Playback scrubbing with the playhead using mouse click-drag, shift-scroll, or other devices #29)
• Right click = subtitle outpoint

...which causes me to constantly mess up my inpoints because I intuitively left-click to move the playhead (it didn't even occur to me until recently that it could be the middle mouse button actually). I kinda understand the logic between the playhead button being centered between the left and right buttons, but it still feels unnatural coming from a video editing background.

I know this is a bit of a melting-pot of multiple issues, but I'm not sure if it makes sense to file half a dozen tickets for that when they behavior all kinda ties together...