bugfix for configuring PWM on D6 and D13 too early. (thanks to Limor Fried)

was starting PWM on these pins too soon - in init() instead of when analogWrite() was called.  as a result doing output on port registers directly failed.

cores/arduino/wiring.c

@@ -280,10 +280,6 @@ void init()
 #endif
 
 #if defined(TCCR4A) && defined(TCCR4B) && defined(TCCR4D) /* beginning of timer4 block for 32U4 and similar */
-	sbi(TCCR4A, COM4A1);	// clear channel A on output compare match
-	cbi(TCCR4A, COM4A0);
-	sbi(TCCR4C, COM4D1);	// clear channel D on output compare match
-	cbi(TCCR4C, COM4D0);
 	sbi(TCCR4B, CS42);		// set timer4 prescale factor to 64
 	sbi(TCCR4B, CS41);
 	sbi(TCCR4B, CS40);

cores/arduino/wiring_analog.c

@@ -210,6 +210,9 @@ void analogWrite(uint8_t pin, int val)
 			case TIMER4A:
 				//connect pwm to pin on timer 4, channel A
 				sbi(TCCR4A, COM4A1);
+				#if defined(COM4A0)		// only used on 32U4
+				cbi(TCCR4A, COM4A0);
+				#endif
 				OCR4A = val;	// set pwm duty
 				break;
 			#endif
@@ -234,6 +237,9 @@ void analogWrite(uint8_t pin, int val)
 			case TIMER4D:				
 				// connect pwm to pin on timer 4, channel D
 				sbi(TCCR4C, COM4D1);
+				#if defined(COM4D0)		// only used on 32U4
+				cbi(TCCR4C, COM4D0);
+				#endif
 				OCR4D = val;	// set pwm duty
 				break;
 			#endif