Possible to set accuracy of measurements. Fix #83
´´´json
"tools":
{
        { ' Meassure lengths
         "type": "MeasureLine",
         "accuracy": "AccuracyOfMeasurements"
        },
        { ' Meassure areas
         "type": "MeasureArea",
         "accuracy": "AccuracyOfMeasurements"
        }
}