v0.2.0-alpha

Fixes MsgBuilder using the msgh_remote_port field of mach_header_t for the reply port.

Other changes:

• Drop implementations for Mach port name wrappers no longer panic on error.
• Debug implementations are now provided for all public types.
• AsRawName is now implemented for references to Mach port name wrappers.
• Documentation is slightly improved.

Fix docs.rs build.

v0.1.0-alpha2

Bump the version for crates.io.