related_post_gen benchmark

[PMunch]

Oh right, yeah that rules out xxhash unless we want to re-implement the entire 
thing in Nim. But fxhash only requires casting a position in a string to an 
unsigned integer, that's supported in the VM isn't it? Doesn't really have to 
be pointers either, this also works:
    
    
    result.hashWord(cast[UncheckedArray[uint64]](x[0])[pos div 8])
    
    
    Run