textproc/py-emeraldtree: New port

EmeraldTree is a fork of ElementTree - the main differences are:

- It has a slightly different API for handling of text: it uses unicode
  objects as children (not as "tail" attributes of the elements)
- API cleanups, removing backward compatibility
- Better unicode support
- PolyglotWriter (for writing html5 that is also well-formed xml)
- Other improvements / optimizations

WWW: https://github.com/moinwiki/emeraldtree