refactor example code

src/com/xeiam/examples/Example1.java

src/com/xeiam/examples/Example2.java

src/com/xeiam/examples/SwingChart2.java

src/com/xeiam/examples/SwingChart3.java

src/com/xeiam/examples/SwingChart4.java

src/com/xeiam/examples/SwingChart5.java

src/com/xeiam/swing/QuickChart.java

src/com/xeiam/swing/SwingHelper.java

src/com/xeiam/xcharts/BitmapEncoder.java