Remove corpus-specific tag maps from the language data for languages
without custom tokenizers. For languages with custom word segmenters
that also provide tags (Japanese and Korean), the tag maps for the
custom tokenizers are kept as the default.
The default tag maps for languages without custom tokenizers are now the
default tag map from `lang/tag_map/py`, UPOS -> UPOS.
* Add correct stopwords for Slovak language
* Add SNK Tags
* Disable formatting lint for TAGS
* Add example sentences for Slovak language
* Add slovak numerals in base form
* Add lex_attrs to sk init
* Add contributor agreement
* Add base classes for more languages
* Add test for language class initialization
Make sure language can be initialize – otherwise, it's difficult to catch serious errors in the test suite, because languages are lazy-loaded
