Grapheme

Added support for Unicode 13.

Drops support for python 3.4 & 3.5. Now tested on python 3.6 - 3.8.
No API changes

Added support for Unicode 12.

No API changes

Added support for Unicode 11.

Added `grapheme.UNICODE_VERSION`.

No other API changes

Added a few new functions:

* `grapheme.safe_split_index`, which can find the highest grapheme boundary index in a given string without traversing the full grapheme sequence.
* `grapheme.startswith`, which tests that a given string starts with the same grapheme sequence as a given prefix.
* `grapheme.endswith`, which tests that a given string ends with the same grapheme sequence as a given suffix.

Performance improvements

No new functionality, but noticably better performance.

* Adds `grapheme.contains`
* Bugfix for empty strings