By Jibran Ahmad and Katharine Houreld PESHAWAR/ISLAMABAD, Pakistan (Reuters) - As Pakistanis unite in grief over the killings of 132 schoolchildren by the Pakistani Taliban, several other militant groups have been quick to condemn the carnage too. Most such groups have slaughtered civilians themselves, but the wave of outrage following the school attack is threatening the relative freedom they enjoy in Pakistan. The country is home to a range of armed militant groups. Some, like the Pakistani Taliban, fight against the state. ...