add Liquid Crystal I2C Library

libraries/Arduino-LiquidCrystal-I2C-library-master/examples/HelloWorld/HelloWorld.ino

@@ -0,0 +1,20 @@
+#include <Wire.h> 
+#include <LiquidCrystal_I2C.h>
+
+// Set the LCD address to 0x27 for a 16 chars and 2 line display
+LiquidCrystal_I2C lcd(0x27, 16, 2);
+
+void setup()
+{
+	// initialize the LCD
+	lcd.begin();
+
+	// Turn on the blacklight and print a message.
+	lcd.backlight();
+	lcd.print("Hello, world!");
+}
+
+void loop()
+{
+	// Do nothing here...
+}