Get the handle of a field
                Get the handle of a field by using the GetField method.
Example
The goal is to get the handle of the field Country.
The client sends:
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "GetField",
  "handle": 1,
  "params": [
    "Country"
  ]
}
                The engine returns:
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "qReturn": {
      "qType": "Field",
      "qHandle": 2
    }
  }
}
                The field has the handle 2.