Add Wire.end()

Wire.cpp

 	NVIC_ENABLE_IRQ(IRQ_I2C0);
 }
 
+void TwoWire::end()
+{
+	NVIC_DISABLE_IRQ(IRQ_I2C0);
+	I2C0_C1 = 0;
+	CORE_PIN18_CONFIG = 0;
+	CORE_PIN19_CONFIG = 0;
+	SIM_SCGC4 &= ~SIM_SCGC4_I2C0; // TODO: use bitband
+}
+
 void i2c0_isr(void)
 {
 	uint8_t status, c1, data;
   begin((uint8_t)address);
 }
 
+void TwoWire::end()
+{
+  TWCR &= ~(_BV(TWEN) | _BV(TWIE) | _BV(TWEA));
+  digitalWrite(SDA, 0);
+  digitalWrite(SCL, 0);
+}
+
 void TwoWire::setClock(uint32_t frequency)
 {
   TWBR = ((F_CPU / frequency) - 16) / 2;

Wire.h

 #include "Arduino.h"
 
 #define BUFFER_LENGTH 32
+#define WIRE_HAS_END 1
 
 extern "C" void i2c0_isr(void);
 
     void begin();
     void begin(uint8_t);
     void begin(int);
+    void end();
     void setClock(uint32_t);
     void beginTransmission(uint8_t);
     void beginTransmission(int);