Support TIMER1C

Some devices, such as the atmega2560 or the atmega256rfr2 have a timer1c
output. It seems this output is not connected to anything on the Arduino
Mega, but this allows using it on third party hardware nonetheless.

cores/arduino/Arduino.h

@@ -194,20 +194,21 @@ extern const uint8_t PROGMEM digital_pin_to_timer_PGM[];
 #define TIMER0B 2
 #define TIMER1A 3
 #define TIMER1B 4
-#define TIMER2  5
-#define TIMER2A 6
-#define TIMER2B 7
+#define TIMER1C 5
+#define TIMER2  6
+#define TIMER2A 7
+#define TIMER2B 8
 
-#define TIMER3A 8
-#define TIMER3B 9
-#define TIMER3C 10
-#define TIMER4A 11
-#define TIMER4B 12
-#define TIMER4C 13
-#define TIMER4D 14	
-#define TIMER5A 15
-#define TIMER5B 16
-#define TIMER5C 17
+#define TIMER3A 9
+#define TIMER3B 10
+#define TIMER3C 11
+#define TIMER4A 12
+#define TIMER4B 13
+#define TIMER4C 14
+#define TIMER4D 15
+#define TIMER5A 16
+#define TIMER5B 17
+#define TIMER5C 18
 
 #ifdef __cplusplus
 } // extern "C"

cores/arduino/wiring_analog.c

@@ -160,6 +160,14 @@ void analogWrite(uint8_t pin, int val)
 				break;
 			#endif
 
+			#if defined(TCCR1A) && defined(COM1C1)
+			case TIMER1C:
+				// connect pwm to pin on timer 1, channel B
+				sbi(TCCR1A, COM1C1);
+				OCR1C = val; // set pwm duty
+				break;
+			#endif
+
 			#if defined(TCCR2) && defined(COM21)
 			case TIMER2:
 				// connect pwm to pin on timer 2

cores/arduino/wiring_digital.c

@@ -84,6 +84,9 @@ static void turnOffPWM(uint8_t timer)
 		#if defined(TCCR1A) && defined(COM1B1)
 		case TIMER1B:   cbi(TCCR1A, COM1B1);    break;
 		#endif
+		#if defined(TCCR1A) && defined(COM1C1)
+		case TIMER1C:   cbi(TCCR1A, COM1C1);    break;
+		#endif
 		
 		#if defined(TCCR2) && defined(COM21)
 		case  TIMER2:   cbi(TCCR2, COM21);      break;