Added word count (#85), fixed html escape splitting bug (#89)

New options to (as accurately as I could) count words in the detail text. It will ignore common free-standing HTML escape characters like &amp and &nbsp in the count, as well as ignore cases of double spacing, punctuation, etc.

New options and their defaults for word counting:
~~~
// whether to count and display the number of words inside the collapsed text
showWordCount: false,
 
// What to display around the counted number of words, set to '{{count}}' to show only the number
countWordsText: ' ({{count}} words)',
~~~

The html escape-character splitting has been resolved by moving the alienated characters after the "&" from the beginning of detail text to the end of summary text. (It will not move these characters if the elements are in a block display because all of summary text is replaced by detail text on reveal in these cases.)