Add vrt-augment-name-attrs: Add ne structures based on NER attributes

[janiemi]

Add vrt-augment-name-attrs, a VRT tool to add ne structures (elements) and their attributes (annotations) based on positional NER attributes (nertag2, nertags2, nerbio2) as produced by vrt-finnish-nertag.

Usage:

usage: vrt-augment-name-attrs [-h]
                              [--out file | --in-place | --backup bak | --in-sibling EXT]
                              [--version] [--word attr] [--lemma attr] [--nertag attr]
                              [--multi-nertag attr] [--maximal-only]
                              [file]

Augment VRT input containing positional name attributes with <ne> structures with
attributes. The tool expects a positional attribute to contain NER tags for maximal names,
matching the regular expression "(Ena|Nu|Ti)mex[A-Z][a-z]+[A-Z][a-z]+-[BEF]", as produced by
vrt-finnish-nertag. Another attribute can contain a set of NER tags for possible nested
names, with "-N" appended where N is the nesting level.

positional arguments:
  file                  input file (default stdin)

options:
  [… Standard VRT tool options …]
  --word attr           positional attribute name for word form is attr (default: "word")
  --lemma attr          positional attribute name for base form (lemma) is attr; if the
                        input does not contain attr, use word forms in the place of lemmas
                        (specify "" to suppress a warning) (default: "lemma")
  --nertag attr         positional attribute name for maximal NER tag is attr (default:
                        "nertag2")
  --multi-nertag attr   positional attribute name for multiple (nested, non-maximal) NER
                        tags is attr (default: "nertags2")
  --maximal-only        enclose only maximal names, no nested ones

Tests are included for the tool.