By Nidal al-Mughrabi and Bassam Masoud CAIRO/GAZA (Reuters) – Israeli tanks advanced deep into a town in the central Gaza Strip on Thursday after days of relentless bombardment that forced tens of thousands of already displaced Palestinian families to flee in a new exodus. A Palestinian journalist posted pictures of Israeli tanks near a mosque in a built-up area of Bureij, the armoured contingent having apparently advanced from orchards on the eastern outskirts. Further south, Israeli forces struck the area around a hospital in the heart of Khan Younis, the Gaza Strip’s main southern city, whe…