Updated filter-rt to handle unseen substrings
Fixed filter-rt to handle intervening non-terminal
Some efficiency improvements to filtering
Adding span to rule with 0 NT, giving actual span of the phrase + Halfway done HyperGraph Transformation
Add NonTerminal Position in Translation Rule Hiero
Implementing HyperGraph on Hiero
Adding some documentation for Hiero Hypergraph
Merge branch 'feature/hiero_hypergraph' into develop
Finalizing Hypergraph transformation and some refactoring
Merge branch 'master' of https://github.com/neubig/travatar into develop