North American lumber prices are on the decline again as questions continue to linger about the current state of the housing market.    Lumber futures fell 3% to $402 per thousand board feet on Tuesday, and the essential building commodity has suffered an eight-day losing streak that has erased 21% off of futures' pricing.    The 23% price decline seen in lumber so far in February is an about-face from its strength seen in January, in which the commodity surged 37%.    But analysts at Raymond James expect a ...