(Refiles to new USN)* Oil extends slide close to $45 a barrel* Retails, prospect of ECB action lifts Europe shares* Dollar gains vs yen and euro in choppy tradeBy Nigel StephensonLONDON, Jan 13 (Reuters) - Oil prices slid on Tuesday to their lowest in almost six years, but European shares rose as investors focused on expectations that policymakers would soon take action to prevent the euro zone sl