checked_sum 0.1.0

A library safely summing up iterators.
Documentation
## `checked_sum`

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Utility crate for summing up iterators in a safe way. The `CheckedSum`
trait is implemented for any iterator of items implementing `CheckedAdd`,
which in turn is implemented for all integer primitives but can also be
implemented for other types like newtypes wrapping integers.

```rust
use checked_sum::CheckedSum;

// If the sum fits into the type, it is returned
let numbers = vec![1u8, 2, 3, 4, 5];
assert_eq!(numbers.into_iter().checked_sum(), Some(15),);

// If the sum overflows, `None` is returned
let numbers = vec![255u8, 1];
assert_eq!(numbers.into_iter().checked_sum(), None,);
```