URL list (URLs widget)

The keys (and associated values) for the URLs lists are the following:

Key	Type	Default	Value	Remark
url	string	—	file url (absolute)	be careful to include the indication http://
encoding	string	—	file encoding	cf. Python doc (codecs)
annotation_key	string	—	annotation key	—
annotation_value	string		annotation value	—

Example:

[
    {
        "url":              "http://www.imsdb.com/scripts/Alien.html",
        "encoding":         "iso-8859-1",
        "annotation_key":   "genre",
        "annotation_value": "sci-fi"
    },
    {
        "url":              "http://www.imsdb.com/scripts/Pulp-Fiction.html",
        "encoding":         "iso-8859-1",
        "annotation_key":   "genre",
        "annotation_value": "crime"
    }
]