Drop 'cue' from 'A cue line position/alignment'

No other terms in this section except 'A cue box' include 'cue'.
Quote strings in the syntax section for consistency

Compare with e.g. the "align" setting.
Merge pull request #93 from foolip/quote-strings

Quote strings in the syntax section for consistency
Merge pull request #91 from foolip/a-cue-line

Drop 'cue' from 'A cue line position/alignment'