done in mail body format

internal/task/task.go

@@ -180,6 +180,10 @@ func (t *Task) FormatBody() string {
 		fields[FIELD_DUE] = t.Due.String()
 	}
 	order = append(order, []string{FIELD_PROJECT, FIELD_VERSION, FIELD_ID}...)
+	if t.Done {
+		fields[FIELD_DONE] = "true"
+		order = append(order, FIELD_DONE)
+	}
 
 	keyLen := 0
 	for _, f := range order {

internal/task/task_test.go

@@ -357,6 +357,7 @@ id:
 				Version: version,
 				Action:  action,
 				Project: project,
+				Done:    true,
 				Due:     task.NewDate(2021, 1, 30),
 				Message: &mstore.Message{
 					Body: "previous body",
@@ -368,6 +369,7 @@ due:     2021-01-30 (saturday)
 project: project
 version: 6
 id:      an id
+done:    true
 
 Previous version: