handle end-of-line hyphenation

[JonathanReeve]

We have a few options here:

• use <pc force="weak">-</pc> in the TEI, which can transform into a soft hyphen or ­ entity.
• use the soft hyphen unicode character

The unicode character is more in keeping with our methodology thus far (using, say, quotation dashes in unicode instead of XML/HTML entity codes), but definitely harder to read and spot in the code.

It's probably best to replace these manually, by checking against the Norton or Viking editions.

[JonathanReeve]

Abandoning this issue in favor of #70.