Version   Changes
--------  --------------------------------------------------------------------
0.5.1     Changed internal fn, so that macro Dec! can be used in a const
          context.

0.5.0     Reduced MAX_N_FRAC_DIGITS to 18.
          If the exact result of Multiplication or Division would exceed
          MAX_N_FRAC_DIGITS, a result rounded to MAX_N_FRAC_DIGITS is returned
          instead of panicking.

0.4.1     Fixed mismatch between impl of PartialOrd and derived impl of Ord.

0.4.0     Added impls of trait DivRounded for native integers.
          Added traits AsIntegerRatio and Quantize as well as corresponding
          implementations for Decimal and native ints.

0.3.1     Check resulting n_frac_digits > MAX_N_FRAC_DIGITS in fn mul.

0.3.0     Added "checked" variants of Add, Div, Mul, Rem and Sub as well as
          corresponding implementations.

0.2.0     Added conversion from `f32` and `f64` to `Decimal`.

0.1.0     First public version.
