Structure-Activity Relationship Studies of CNS Agents. Part 6. Effect of the Terminal Amide Fragment on 5-HT1A and 5-HT2 Receptor Affinity for N-(3-(4-Aryl-1-piperazinyl)propyl) Derivatives of 3,4- Dihydroquinolin-2(1H)-one and Its Isomeric Isoquinolinones.