A little of coordination for Rosettacode

[bearophile]

> Instead of using toString() maybe it's better to add a 
> printTape, and let run() return nothing. I have also converted 
> UTM to a struct, because for this little program it doesn't 
> need to be a class (and there is no need of new).

I meant the opposite, sorry:

printTape() ==> toString()

Bye,
bearophile