[Feature request for v2] Debugging option to help editing recorded asciicast file

[KurtPfeifle]

It occurred to me that it would be very useful if there was a way to display/log/indicate the current line of a v2 line when replaying a recorded session.

For such a feature to be useful it doesn't even need to display the line number permanently + syncronically to the replay. It would even suffice if we could invoke some keyboard shortcut while the replay is paused (which can be invoked with pressing [space] already), and this keyboard shortcut then displays the info about the current line. It could even go to a logfile (along with the actual content of the line), so it can be identified + looked at in context later.

(Possible context: issue asciinema/asciinema#252)