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/inbreeding/README.md

@@ -7,7 +7,7 @@
 use ./bins/inbreeding
 ```
 ```bash
-const PRNG_SEED = 123
+const PRNG_SEED = "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
 const OPTS = {
     nb_bytes: (10 * 1_024),
     k: 10,