A Java implementation of Twig (mostly translated from the original PHP source)

This is just an exercise (though preg_match_* functions may make it futile) in writing Java by taking something I'm interested in (Twig and language parsing) written in something I'm very familiar with (PHP) and writing it in something I'm still pretty familiar with (Java) but not as much as the other thing. I claim no creative authorship on Twig except the Java specifics of this implementation.