Timecodes shown on waveform while setting in/out points for a subtitle could be clearer

[nekohayo]

There are two timecodes being shown, in/out point and duration. It would be nice to make it a bit clearer which is which, both as a learning mechanism for new users and as a quick visual cue otherwise.

The solution doesn't have to be overly complicated, thanks to the power of unicode, you could just prefix/append ⇤ ⇥ arrows (or the word "In-point:" / "Start:" or "Out-point:" / "End :" to the strings... for example

• ⇤ 0:06:30.382 (for the in-point)
• 0:06:34.335 ⇥ (for the out-point)
• Duration:\n 3.95 secs (as per Simplify the "duration" timecode to be human-readable #32)