0.5.8

This version includes following changes.

• Move to the new github repository msgpack/msgpack-c
• Support the new deserialization specification
• fixes the problem of unpack helpers for array and map with 32bit compilers (#37, #38)
• Other bug fixes and refactoring: #46, #41, #36, #35, #33, #32, #30, #29, #28, #27, #26, #25, #8, #3
• Update of documents: #23, #18, #17