Brings some updates to comply with final standard

…ad of 'u')

… the exponential indicator 'e', both previously lowercase, are now 'Y' and 'E' (uppercase);

the significant digit indicator 'p' is now 'S' (uppercase) --> significat digit is still NOT implemented yet

…n' and 'open' have been replaced with null and the double-dot notation ['..'] respectively;

general overwork of intervals and consecutives to deal with open beginnings and open ends

…eason; year overflow for northern winter/southern sommer still not considered

…pecification expression

…tion of the new spec but keep the old way with brackets

…tion of the new spec but keep the old way with brackets

…into develop

…g way with brackets

Partial merge of fork from https://github.com/saw-leipzig/python-edtf.git

- Tests are failing due to testInterval(), but are being run correctly. On Python 3.12, `nose` is failing. We should upgrade to `nose2`, or more likely, switch from unittest + nose to pytest.
- Move tox config to setup.cfg for now
- TODO move to pyproject.toml instead of setup.cfg
- TODO remove .travis.yml

Remove setup.cfg and setup.py in favor of pyproject.toml

Nose and Tox are next to go. Nose seems to be failing on Python 3.10, no need for it any more as pytest should cover its features. Likely no need for tox either as we are using the matrix strategy in Github Actions, though it could be useful for local dev

Anticipate None for date_display #62

Update Readme

drop six dependency

fix alerts formatting in readme

62 verify related fields