Tens of thousands of homes were still without power yesterday as the cost of the hurricane-force winds that battered Scotland on Thursday was estimated at ?100 million. Some are not due to be reconnected until tomorrow.  While the central belt recovered from the worst storm in a decade, areas farther north were still being battered by wind and heavy snowfall.  The power cuts, early closures of businesses, blocked roads and people heeding advice to stay at home all contributed to the predicted loss to the economy.  Caroline Roxburgh, from PricewaterhouseCoopers, said that more harsh weather could worsen the problems.  "Retailers who are already facing arguably the toughest trading conditions in recent