(Reuters) - Security forces cleared a Cairo mosque after a gunbattle with followers of the Muslim Brotherhood on Saturday, while Egypt's army-backed government, facing deepening chaos, considered banning the Islamist group. Three Reuters witnesses saw gunmen shoot from a window of the al-Fath mosque, where supporters of deposed president Mohamed Mursi had taken shelter Another gunman was shown on television shooting from the mosque's minaret and soldiers outside It was not clear if anyone died in the clashes - the fourth day of violence in Egypt, which has killed almost 800 people. Troubles were also reported in the second city...