WASHINGTON — The Federal Aviation Administration issued an emergency order Wednesday grounding all Boeing 737 Max aircraft in the wake of a crash of an Ethiopian airliner that killed 157 people, a reversal for the U.S. after federal aviation regulators had maintained it had no data to show the jets are unsafe.The decision came hours after Canada joined some 40 other countries in barring the Max 8 from its airspace, saying satellite tracking data showed possible but unproven [...]