GitLab

* Better heuristic for token-classification pipeline.

Relooking at the problem makes thing actually much simpler,
when we look at ids from a tokenizer, we have no way in **general**
to recover if some substring is part of a word or not.

However, within the pipeline, with offsets we still have access to the
original string, so we can simply look if previous character (if it
exists) of a token, is actually a space. This will obviously be wrong
for tokenizers that contain spaces within tokens, tokenizers where
offsets include spaces too (Don't think there are a lot).

This heuristic hopefully is fully bc and still can handle non-word based
tokenizers.

* Updating test with real values.

* We still need the older "correct" heuristic to prevent fusing
punctuation.

* Adding a real warning when important.