/**
 * Create a radiobutton inside the current or given toggle group. The optional value parameter will be matched against
 * the extension property `selectedValueProperty()` on Toggle Group. If the #ToggleGroup.selectedValueProperty is used,
 * it's value will be updated to reflect the value for this radio button when it's selected.
 * 
 * Likewise, if the `selectedValueProperty` of the ToggleGroup is updated to a value that matches the value for this 
 * radiobutton, it will be automatically selected.
 */
fun Node.radiobutton(text: String? = null, group: ToggleGroup? = getToggleGroup(), value: Any? = null, op: (RadioButton.() -> Unit)? = null)