refactored example classes and QuickChart

src/com/xeiam/examples/Example2.java

src/com/xeiam/examples/Example3.java

src/com/xeiam/examples/Example4.java

src/com/xeiam/examples/SwingChart3.java

src/com/xeiam/swing/QuickChart.java

src/com/xeiam/swing/SwingWrapper.java

src/com/xeiam/xcharts/QuickChart.java