support proper 32-byte RNG seeds

• add optional $.help to argument err of error throw
• parse prng_seed: [u8; 32] in rng and inbreeding
• compute the "local" seed by hashing the "global" seed, the strategy and the iteration index
• pass --prng-seed: string, a 64-char long seed to inbreeding run

bins/rng/src/main.rs

@@ -27,7 +27,7 @@ struct Cli {
 fn main() {
     let cli = Cli::parse();
 
-    let mut rng = StdRng::from_seed(cli.prng_seed.into());
+    let mut rng = StdRng::from_seed(cli.prng_seed);
 
     for _ in 0..cli.n {
         println!("{}", rng.gen::<u8>());