Add driver for TMP102 low-power digital temperature sensor (#141)

* tmp102: add driver and example

examples/tmp102/main.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/tmp102"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{
+		Frequency: machine.TWI_FREQ_400KHZ,
+	})
+
+	thermo := tmp102.New(machine.I2C0)
+	thermo.Configure(tmp102.Config{})
+
+	for {
+
+		temp, _ := thermo.ReadTemperature()
+
+		print(fmt.Sprintf("%.2f°C\r\n", float32(temp)/1000.0))
+
+		time.Sleep(time.Millisecond * 1000)
+	}
+
+}