s/OpenByName/Open/g and d/OpenByNumber/

This shortens OpenByName() to Open() and removes OpenByNumber(). The concept of
number is not removed, it's still possible to open a bus by number, but a base10
string representation of the number is now needed. In practice, I haven't found
a real use for OpenByNumber().

This simplify the API surface, less functions leads to simpler to understand
API.

This is a breaking change.

devices/apa102/apa102_test.go

@@ -558,7 +558,7 @@ func TestInit(t *testing.T) {
 //
 
 func Example() {
-	bus, err := spi.OpenByName("")
+	bus, err := spi.Open("")
 	if err != nil {
 		log.Fatalf("failed to open SPI: %v", err)
 	}

devices/bme280/bme280_test.go

@@ -140,7 +140,7 @@ func TestCalibrationInt(t *testing.T) {
 //
 
 func Example() {
-	bus, err := i2c.OpenByName("")
+	bus, err := i2c.Open("")
 	if err != nil {
 		log.Fatalf("failed to open I²C: %v", err)
 	}

devices/ds248x/ds248x_test.go

@@ -32,7 +32,7 @@ func TestInit(t *testing.T) {
 
 func Example() {
 	// Open the I²C bus to which the DS248x is connected.
-	i2cBus, err := i2c.OpenByName("")
+	i2cBus, err := i2c.Open("")
 	if err != nil {
 		fmt.Println(err)
 		return
@@ -72,7 +72,7 @@ func TestRecordInit(t *testing.T) {
 	}
 	host.Init()
 
-	i2cReal, err := i2c.OpenByName("")
+	i2cReal, err := i2c.Open("")
 	if err != nil {
 		t.Fatal(err)
 	}

devices/ssd1306/ssd1306_test.go

@@ -77,7 +77,7 @@ func TestDraw1D(t *testing.T) {
 //
 
 func Example() {
-	bus, err := i2c.OpenByName("")
+	bus, err := i2c.Open("")
 	if err != nil {
 		log.Fatalf("failed to open I²C: %v", err)
 	}