near-bigdecimal

Big decimal for NEAR smart contracts

Examples

```rust let a = BigDecimal::from(3u128); let b = BigDecimal::from(10u128); let c = BigDecimal::from(49_u128);

asserteq!((a + b).roundu128(), 13); asserteq!((a * b).roundu128(), 30); asserteq!((b / a).roundu128(), 3); asserteq!((b.pow(2)).roundu128(), 100); asserteq!((c.sqrt()).roundu128(), 7); ```