Concurrency Kit 0.2.18 发布，并发工具包

Concurrency Kit提供了大量的并发原语，安全的内存回收机制和无阻塞的数据结构设计，以帮助高性能并行系统的设计和实施。

发布日志: This release implements an improved finer-grained memory barrier interface, and also implementes lighter-weight ck_epoch_synchronize functionality. ck_epoch_synchronize will no longer execute any deferred callbacks (as documented, ck_epoch_barrier must be used). The latter interface plays nicely for integrations that wish to time reclamation overheads