LONDON (Reuters) - European shares opened higher on Thursday, bolstered by relatively robust earnings reports despite economic weakness, while the euro inched lower as uncertainty over how the euro zone will handle crises in Spain and Greece dragged on. The FTSE Eurofirst index of top European shares was up 0.2 percent at 0820 GMT, helped by UK corporate results including from oil major Royal Dutch Shell . Small gains by London's FTSE 100 and Frankfurt's DAX canceled out minor dips in Paris and Madrid . ...