DateRange rendering, algorithm quite buggy on boundaries

[glorieux-f]

Please follow the general troubleshooting steps first:

• [x] I read the README and followed the instructions.
• [x] I am sure that the used CSL metadata follows the CSL schema.
• [x] I use a valid CSL stylesheet

Bug reports:

data	citeproc-php	zotero
"date-parts": [[1946, 12, 31], [1947, 1, 1]]	1946, December 31–1	1946–1947, December 31–January 1
"date-parts": [[1946, 12], [1947, 1]]	1946, December–January	1946–1947, December–January
"date-parts": [[1946, 9], [1946, 10]]	1946, September	1946, September–October

Used CSL stylesheet:

apa.csl

Used CSL metadata

[

    {
        "id": "n1", 
        "type": "article-newspaper",
        "title": "Date range bugs",
        "issued": {
            "date-parts": [[1946, 12, 31], [1947, 1, 1]]
        }
    },
    {
        "id": "n2", 
        "type": "article-newspaper",
        "title": "Date range bugs",
        "issued": {
            "date-parts": [[1946, 12], [1947, 1]]
        }
    },
    {
        "id": "n3", 
        "type": "article-newspaper",
        "title": "Date range bugs",
        "issued": {
            "date-parts": [[1946, 9], [1946, 10]]
        }
    }
]