Philip Merrill, the prominent publisher and former diplomat whose body was found floating in the Chesapeake Bay on Monday, suffered from a heart condition and apparently took his own life, his family said last night. Merrill, 72, was found with a shotgun wound to the head and a small anchor tied around one or both ankles, according to a source familiar with the investigation. ~~~~snip~~~~ In 1996, former CIA director William E. Colby died from drowning and exposure after falling from a canoe off Charles County. ~~~~snip~~~~~ In 1978, another former high-level CIA employee, John A. Paisley, disappeared while sailing...