Added explicit exposition on half-open nature of list indexes
Added link to documentation on lists
Merge remote-tracking branch 'wltrimbl/half-open' into gh-pages

Actually, I merged origin/pr/95, because:

  git://github.com/wltrimbl/bc.git half-open

doesn't seem to exist anymore ;).

Minor quibbles to be resolved later:

* '--' vs. a Unicode em-dash (U+2014 EM DASH), but I'm not sure how
  IPython handles charsets/encodings.
* Bold vs. italics in "elements returned **include** the **starting**
  index but **exclude** the **final** index", because I like:

    * Bold to pick out key terms (page-level emphasis)
    * Italics to stress phrases (sentence-level emphasis)

Neither of those are important enough to keep this out of the main
branch.

* wltrimbl/half-open:
  Added link to documentation on lists
  Added explicit exposition on half-open nature of list indexes