* Improve handling of missing NER tags
GoldParse can accept missing NER tags, if entities is provided
in BILUO format (rather than as spans). Missing tags can be provided
as None values.
Fix bug that occurred when first tag was a None value. Closes#2603.
* Document specification of missing NER tags.
* Classes for Ukrainian; small fix in Russian.
* Contributor agreement
* pymorphy2 initialization split for ru and uk (#3327)
* stop-words fixed
* Unit-tests updated
<!--- Provide a general summary of your changes in the title. -->
## Description
This PR adds the abilility to override custom extension attributes during merging. This will only work for attributes that are writable, i.e. attributes registered with a default value like `default=False` or attribute that have both a getter *and* a setter implemented.
```python
Token.set_extension('is_musician', default=False)
doc = nlp("I like David Bowie.")
with doc.retokenize() as retokenizer:
attrs = {"LEMMA": "David Bowie", "_": {"is_musician": True}}
retokenizer.merge(doc[2:4], attrs=attrs)
assert doc[2].text == "David Bowie"
assert doc[2].lemma_ == "David Bowie"
assert doc[2]._.is_musician
```
### Types of change
enhancement
## Checklist
<!--- Before you submit the PR, go over this checklist and make sure you can
tick off all the boxes. [] -> [x] -->
- [x] I have submitted the spaCy Contributor Agreement.
- [x] I ran the tests, and all new and existing tests passed.
- [x] My changes don't require a change to the documentation, or if they do, I've added all required information.
* splitting up latin unicode interval
* removing hyphen as infix for French
* adding failing test for issue 1235
* test for issue #3002 which now works
* partial fix for issue #2070
* keep the hyphen as infix for French (as it was)
* restore french expressions with hyphen as infix (as it was)
* added succeeding unit test for Issue #2656
* Fix issue #2822 with custom Italian exception
* Fix issue #2926 by allowing numbers right before infix /
* splitting up latin unicode interval
* removing hyphen as infix for French
* adding failing test for issue 1235
* test for issue #3002 which now works
* partial fix for issue #2070
* keep the hyphen as infix for French (as it was)
* restore french expressions with hyphen as infix (as it was)
* added succeeding unit test for Issue #2656
* Fix issue #2822 with custom Italian exception
* Fix issue #2926 by allowing numbers right before infix /
* remove duplicate
* remove xfail for Issue #2179 fixed by Matt
* adjust documentation and remove reference to regex lib
* Fix matching on extension attrs and predicates
* Fix detection of match_id when using extension attributes. The match
ID is stored as the last entry in the pattern. We were checking for this
with nr_attr == 0, which didn't account for extension attributes.
* Fix handling of predicates. The wrong count was being passed through,
so even patterns that didn't have a predicate were being checked.
* Fix regex pattern
* Fix matcher set value test
* Change retokenize.split() API for heads
* Pass lists as values for attrs in split
* Fix test_doc_split filename
* Add error for mismatched tokens after split
* Raise error if new tokens don't match text
* Fix doc test
* Fix error
* Move deps under attrs
* Fix split tests
* Fix retokenize.split
