dashu-base 0.6.0-rc.4

Common trait definitions, error types, and utilities shared by the dashu math crates (integers, floats, rationals, and complex numbers). Defines the core abstractions the library builds on — Approximation, AbsOrd, Signed, SquareRoot, CubicRoot, EstimatedLog2, BitTest, and FloatEncoding — plus the Sign type and conversion errors.