SRT line position support

[kno10]

According to https://docs.lokalise.com/en/articles/5365539-subrip-srt

Line position — X1:… X2:… Y1:… Y2:… after the timestamp denotes the text coordinates.

example:

00:02:36,389 --> 00:02:39,290 X1:203 X2:511 Y1:359 Y2:431
v

This breaks the srt parser.