Subtitles - Add the possibility to synchronize subtitles using a "next sentence" / "previous sentence" shortcut
When facing a desync between subtitles and video, manually guessing the delay in ms is quite tricky and knowing which way to delay is also non-intuitive.
I propose the introduction of two new shortcuts that allows the immediate display of the next (or previous) subtitle sentence as well as delaying all the subtitles to match this display of the sentence.
As a reference, similar functionnality exists in SMPlayer (by default G & Y shortcuts).