stateless client

A stateless client verifies blocks using witnesses instead of storing the full Ethereum state locally.无状态客户端使用见证数据验证区块，而不是在本地存储完整的以太坊状态。

Stateless clients would dramatically lower hardware requirements for running an Ethereum node.无状态客户端将大大降低运行以太坊节点的硬件要求。