By Bassam Masoud, Nidal al-Mughrabi, Dan Williams GAZA/DOHA/JERUSALEM (Reuters) -Israeli forces advancing into the southern Gaza Strip’s main city pounded areas near the biggest hospital still functioning in the enclave on Thursday, sending patients and residents fleeing a battle they feared would lay the city to waste. The heaviest battle of the year so far was under way in Khan Younis, sheltering hundreds of thousands of people who fled the north earlier in the war, now in its fourth month. Residents described heavy fighting and intense bombardment in the north and east of the city and, for …