MADRID/LISBON (Reuters) – A heatwave sweeping southern Europe that has caused hundreds of deaths and huge wildfires in past weeks showed some signs of abating on Monday but continued to move north, including towards Britain where authorities issued an extreme weather warning. Much of Europe is baking in a heatwave that scientists say is consistent with climate change and has pushed temperatures into the mid-40s Celsius (over 110 Fahrenheit) in some regions, with wildfires raging across tinder-dry countryside in Portugal, Spain and France. Temperatures in some parts of southern Europe began to …