ANTICOCCIDIALS. I. SYNTHESES AND ANTICOCCIDIAL ACTIVITY OF 2-AMINO-5-ARYL-1,3,4-OXADIAZOLES, 5-ALKOXY-3-ARYL-1H-1,2,4-TRIAZOLES, AND 3-ARYL-Δ2-1,2,4-TRIAZOLIN-5-ONES