version 1.5.2

Changes since 1.5.1:

• build.rs sets cc::Build::emit_rerun_if_env_changed(false) to prevent some unnecessary rebuilds, particularly when the PATH changes on Windows. See #324.
• Serializing a Hash produces a bytestring instead of an array in formats that support bytestrings (like CBOR). Deserialization is backwards-compatible with the array format.
• Cleanup and edge case fixes in the C and CMake builds.