For loop using iterator `..`

[Araq]

The alternative "design" makes no sense, that's why:
    
    
    let a = stdin.readLine.parseInt
    let b = stdin.readLine.parseInt
    for i in a..b:
      echo "so the iteration order depends on the input? Terrible..."
    
    
    Run

No other programming language that I know of does this either, but my memory of 
other programming languages is fading quickly as I only use Nim. :P