Return index path parameter to handlers

[artemnovichkov]

Current implementation (0.1.0) doesn't have indexPath parameter in different handlers, for example:

let cellItem = NumberCellItem(text: text, textColor: set.colors.first)
cellItem.itemDidSelectHandler = { [weak self, cellItem] in
    if let indexPath = cellItem.indexPath {
        self?.delegate?.didSelect(indexPath)
    }
}

You should check weak cell items every time inside closure body. Please return index paths as a parameter.