Parse repeated lyrics lines and offset, sort by time

[madmini]

• parse repeated lyrics lines such as [00:21.10][00:45.10]Repeating lyrics (e.g. chorus)
• apply [offset:123] tag (and strip other tags)
• sort lines by time
• fix centiseconds being parsed as milliseconds ([00:01.23] was parsed as 1.023s)
• add unit tests cause im paranoid

see also https://en.wikipedia.org/wiki/LRC_(file_format)#File_format)

thanks for the great app!