Error detection and correction
Created after #9 (closed) which became a bit cluttered.
- lines too long/short in duration
- lines too long/short in length of text
- overlaps
- subtitles lines with >2 lines
- empty lines
- hearing impaired subtitles
- unnecessary dots (when a subtitles start or end with four or more dots)
- repeated subtitles
- OCR errors ("I" instead of "l", "0" instead of "O", '' instead of ", etc)
- unnecessary spaces