TANGI SALAUN and GEERT DE CLERCQ FRENCH police shot dead a man who minutes earlier had killed a middle school teacher by slitting his throat in the street in a suburb of Paris. The teacher had shown pupils in his class cartoons of the Prophet Mohammad, which are considered by Muslims to be blasphemous, according to a police source. France's anti-terror prosecutor said it was investigating the attack, which took place in Conflans Sainte-Honorine, a suburb north-west of Paris. The suspected attacker was spotted by a police patrol while carrying a knife a short distance from the scene of the…