Break very long sentences into lines by clauses.
    
    In the spirit of the "sentence per line" documentation style.
    This document happens to have many very long sentences.
    I have arbitrarily chosen 180 characters and split lines longer than that at clause boundaries.
    It may be valuable to rewrite some of these long sentences to be more straightfoward.
    But I'm not touching that here.
    This change should just be asciidoc source formatting, and should not affect either content or rendered presentation.