@Override
    public int size() {
        return list.size();
    }
Creates new grouped list
@param list container to be used by this group list.
            WARNING: GroupList assumes to be the sole manipulator of this list. Parallel editing in other places leads to undefined behaviour
@param defaultGroup default group to assign to new/first element when list is empty
main/src/main/java/cgeo/geocaching/utils/GroupedList.java