NEW YORK, April 15 (Reuters) - New York Times Co. (NYT.N: Quote, Profile, Research), McClatchy Co. (MNI.N: Quote, Profile, Research) and Tribune Co. (TRB.N: Quote, Profile, Research) on Thursday posted sharply lower quarterly earnings on high newsprint costs and depressed advertising sales. The results from the three large publishers underscored the troubles faced by the industry, including...