Import feature

[lyz-code]

Allow the import of data from two kinds of json:

• pydo export.
• taskwarrior export.

An example of a taskwarrior export is the following:

[
  {
    "id": 533,
    "description": "task description",
    "due": "20200415T100000Z",
    "entry": "20200414T164544Z",
    "est": "1",
    "fun": "2",
    "it": "history",
    "modified": "20200423T104903Z",
    "ov": "3",
    "pm": "doing",
    "priority": "5",
    "project": "papers",
    "r": "7d",
    "rparent": "37d3adf5-c6a3-4708-8518-55d61ac0a851",
    "rtype": "periodic",
    "start": "20200423T104903Z",
    "status": "pending",
    "uuid": "f638db0c-1473-4e67-bc41-c567ee6296a5",
    "wp": "4",
    "urgency": 115.425
  }
]

The pydo export json can be obtained through the command once #62 is merged

[lyz-code]

Maybe it's interesting to have a new Task attribute called import_id so we can make the import process idempotent