Gf Ud

Functions to analyse and manipulate dependency trees, as well as conversions between GF and dependency trees. The main use case is UD (Universal Dependencies), but the code is designed to be completely generic as for annotation scheme. This repository replaces the old gf-contrib/ud2gf code. It is also meant to be used in the 'vd' command of GF and replace the supporting code in gf-core in the future.