For months now, Sci-Fi Channel has been publicizing "Tin Man," its six-hour miniseries, arriving tonight, that offers a rebooted take on L. Frank Baum's "The Wonderful Wizard of Oz." It's worth watching because (after a slow start) it builds nicely and imaginatively. It's also worth applauding because - well, because it's a risk, the type the networks mostly are avoiding these days...