By Uditha Jayasinghe COLOMBO (Reuters) -Doctors and bankers were among hundreds of Sri Lankans who marched on Wednesday to demand the government resolve a severe fuel shortage at the heart of the Indian Ocean island’s worst economic crisis in decades or step down. Weeks of street demonstrations against cascading woes such as power cuts and shortages of food and medicine brought a change in government last month after nine people were killed and about 300 injured in protests. Left with just enough fuel for about a week and fresh shipments at least two weeks away, the government restricted suppl…