Declare TwoWire functions as virtual

To make alternative implementations of the TwoWire class (e.g. SoftwareWire for software I2C) work properly being passed to libraries that expect TwoWire type.

libraries/Wire/src/Wire.h

@@ -50,31 +50,31 @@ class TwoWire : public Stream
     static void onReceiveService(uint8_t*, int);
   public:
     TwoWire();
-    void begin();
-    void begin(uint8_t);
-    void begin(int);
-    void end();
-    void setClock(uint32_t);
-    void setWireTimeout(uint32_t timeout = 25000, bool reset_with_timeout = false);
-    bool getWireTimeoutFlag(void);
-    void clearWireTimeoutFlag(void);
-    void beginTransmission(uint8_t);
-    void beginTransmission(int);
-    uint8_t endTransmission(void);
-    uint8_t endTransmission(uint8_t);
-    uint8_t requestFrom(uint8_t, uint8_t);
-    uint8_t requestFrom(uint8_t, uint8_t, uint8_t);
-    uint8_t requestFrom(uint8_t, uint8_t, uint32_t, uint8_t, uint8_t);
-    uint8_t requestFrom(int, int);
-    uint8_t requestFrom(int, int, int);
+    virtual void begin();
+    virtual void begin(uint8_t);
+    virtual void begin(int);
+    virtual void end();
+    virtual void setClock(uint32_t);
+    virtual void setWireTimeout(uint32_t timeout = 25000, bool reset_with_timeout = false);
+    virtual bool getWireTimeoutFlag(void);
+    virtual void clearWireTimeoutFlag(void);
+    virtual void beginTransmission(uint8_t);
+    virtual void beginTransmission(int);
+    virtual uint8_t endTransmission(void);
+    virtual uint8_t endTransmission(uint8_t);
+    virtual uint8_t requestFrom(uint8_t, uint8_t);
+    virtual uint8_t requestFrom(uint8_t, uint8_t, uint8_t);
+    virtual uint8_t requestFrom(uint8_t, uint8_t, uint32_t, uint8_t, uint8_t);
+    virtual uint8_t requestFrom(int, int);
+    virtual uint8_t requestFrom(int, int, int);
     virtual size_t write(uint8_t);
     virtual size_t write(const uint8_t *, size_t);
     virtual int available(void);
     virtual int read(void);
     virtual int peek(void);
     virtual void flush(void);
-    void onReceive( void (*)(int) );
-    void onRequest( void (*)(void) );
+    virtual void onReceive( void (*)(int) );
+    virtual void onRequest( void (*)(void) );
 
     inline size_t write(unsigned long n) { return write((uint8_t)n); }
     inline size_t write(long n) { return write((uint8_t)n); }