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/inspect.nu

@@ -5,7 +5,7 @@ def get-seeds [] [ nothing -> list<string> ] {
     $consts.CACHE | path join '*' | into glob | ls $in | get name | each { path split | last }
 }
 
-export def main [seed: int@get-seeds]: [
+export def main [seed: string@get-seeds]: [
     nothing -> table<
         seed: string,
         timestamp: string,