seckey

Use memsec protected secret memory.

exmaple

```rust use seckey::SecBytes;

let mut secpass = SecBytes::with(1, |buf| buf.copyfromslice(&[8; 8][..]));

{ assert_eq!([8u8; 8], *secpass.read()); }

{ let mut wpass = secpass.write(); wpass[0] = 0; assert_eq!([0, 8, 8, 8, 8, 8, 8, 8], *wpass); } ```