Display line breaks within a cue for WebVTT and SRT transcripts

[Dananji]

Related issue: #750

For the following WebVTT file the display looks as follows;

1
00:00:01.200 --> 00:00:21.000 region:fred align:left
[music]

NOTE End of music, and starting dialog

2
00:00:22.200 --> 00:00:26.600 region:bill align:right
<em>Just</em> before lunch one day, a puppet show 
was put on at school.

3
00:00:26.700 --> 00:00:31.500 region:fred align:left
It was called "Mister Bungle Goes to Lunch".

4
00:00:31.600 --> 00:00:34.500
It was fun to watch.

5
00:00:36.100 --> 00:00:41.300
In the puppet show, Mr. Bungle came to the 
boys' room on his way to lunch.

6
00:00:41.400 --> 00:00:46.200
He looked at his hands. His hands were dirty 
and his hair was messy.

7
00:00:46.300 --> 00:00:51.100
But Mr. Bungle didn't stop to wash his hands 
or comb his hair.

Before	After

[cjcolvar]

Looks good to me.