Updated docs for the new range indexing operator.
Updated example6.
Shortened some comment strings to fit 120 char length.
Added the .uniquify() operator.
Added note in docs about the 'autocomplete_doi' option.
Added note in docs about the '.uniquify()' operator.
Added the 'autocomplete_doi' option keyword.
Merge branch 'master' of https://github.com/nzhagen/bibulous