v0.1.6

• Add random sources, Mersenne Twister engines, SeedSeq and distributions.
• Add BudgetAllocator and fallible Box and Arc construction with try_make.
• Add signal subscriptions and async Ctrl+C, including Windows support.
• Add async Mutex and future by_ref.
• Add SocketAddr parsing and FromStr.
• Add Unix process group extensions and Linux PidFd support.
• Add JSON Reader, quote_string, numeric comparison and Value serde support.
• Add benchmark Suite, Runner, allocation diagnostics and cppstd comparisons.
• Extend floating-point math and fix shortest decimal tie breaking.
• Fix TOML Unicode serialization and aligned allocation for small alignments.
• Simplify Option and Result construction.
• Fix reactor readiness and epoll deregistration.