insert method
Implementation
bool insert(T item, Point<num> atPoint, {dynamic id}) {
if (!containsPoint(atPoint)) return false;
if (_children.isEmpty) {
if (_items.length + 1 <= maxItems || _depth + 1 > maxDepth) {
_items.add(_ItemAtPoint<T>(id, item, atPoint));
return true;
}
_splitItemsBetweenChildren();
}
return _insertItemIntoChildren(item, atPoint, id: id);
}