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