WfBuf rust crate

This crate allow to create mmaped shared anonymous regions of memory, place WfBuf into it using rust placement protocol and use it for data streaming between parent and forked child process. Works only on linux.

Implementation is naive and may be unsound. Stricly for one reader and one writer. There is no queueing, only last written value is read. Implementation try to ensure that at the moment of reading value, reader is accessing the latest written value. You can see how it may be used in tests module in lib.rs.