Lumber futures are heading for their second-straight monthly gain at a time when gloom from the coronavirus pandemic was expected to curb demand.  Prices soared 15% in April and have gained another 15% this month, placing them among the best performing commodities tracked by Bloomberg.  Aggressive supply cuts from big producers such as West Fraser Timber Co. and Canfor Corp. have tightened supplies at a time when people staying in and deciding to fix up their homes, said Kevin Mason, managing director of Vancouver-based ERA Forest Products Research.  “You had ...