English TN sentence-break rules

This artifact is derived from the English portion of the Google Text
Normalization dataset (tn-en_with_types), created for:

Richard Sproat and Navdeep Jaitly. 2016. "RNN Approaches to Text
Normalization: A Challenge."

Corpus source:
https://github.com/rwsproat/text-normalization-data/tree/master/en_with_types

The corpus is based on English Wikipedia. Attribution is also given to the
Wikipedia contributors whose work supplied the underlying text:
https://www.wikipedia.org/

Modifications: icukit's ordered rules were mined from the corpus's
sentence-boundary labels, converted to the icukit break-rules format, and
supplemented with validation witnesses synthesized from each rule's predicates,
which include lexical values mined from the corpus (e.g. `lower` token values);
no corpus sentence or row was read or copied.

The cartlet model file `sentence-tn-cart.json.gz` is a second artifact derived
the same way: a CART model trained on the same corpus's sentence-boundary labels;
no corpus text is included.

The rule artifact, this notice, and the accompanying receipt are distributed
under the Creative Commons Attribution-ShareAlike 4.0 International license.
The full license text is in LICENSE beside this file, and the canonical license
URL is https://creativecommons.org/licenses/by-sa/4.0/.
