dashu-macros 0.6.0

Procedural macros for the dashu math types: create big-number literals at compile time with ubig!, ibig!, fbig!, dbig!, rbig!, and cbig! (plus their static_ variants for const contexts). Each literal follows the same parsing rules as the corresponding dashu type, producing values of UBig, IBig, FBig, RBig, or CBig in any supported base.
Documentation
Create an arbitrary precision rational number ([dashu_ratio::RBig] or [dashu_ratio::Relaxed]).

```rust
# use dashu_macros::rbig;
let a = rbig!(22/7);
let b = rbig!(~-1/13); // use `~` to create a relaxed rational number
let c = rbig!(0x3c/0x5e);
let d = rbig!(~0xff/dd); // the prefix of denomiator can be omitted
let e = rbig!(-2); // denominators can be omitted for integers

// underscores can be used to separate digits
let f = rbig!(107_241/35_291);
```

For an arbitrary base, add `base N`:
```rust
# use dashu_macros::rbig;
let g = rbig!(a3/gp1 base 32);

// it might be necessary to put a underscore to prevent
// Rust from recognizing some digits as prefix or exponent
let h = rbig!(~_100ef/_5ge base 32);
let i = rbig!(_0b102/_0h2 base 32);
let j = rbig!(b102/h2 base 32);
assert_eq!(i, j);
```

For numbers whose the numerator and denominator are small enough (fit in [u32]),
the literal can be assigned to a constant.

```rust
# use dashu_macros::rbig;
use dashu_ratio::{RBig, Relaxed};

const A: RBig = rbig!(-1/2);
const B: Relaxed = rbig!(~3355/15);
```