added line and scatter chart differentiation

...-demo/src/main/java/com/xeiam/xchart/demo/XChartDemo.java

.../java/com/xeiam/xchart/demo/charts/line/ExampleChart.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart01.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart02.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart03.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart04.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart05.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart06.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart07.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart08.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart09.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart10.java

...n/java/com/xeiam/xchart/demo/charts/line/LineChart11.java

.../com/xeiam/xchart/demo/charts/scatter/ScatterChart01.java

...demo/src/main/java/com/xeiam/xchart/example/Example1.java

xchart/src/main/java/com/xeiam/xchart/Chart.java

xchart/src/main/java/com/xeiam/xchart/ChartBuilder.java

xchart/src/main/java/com/xeiam/xchart/LineChart.java

xchart/src/main/java/com/xeiam/xchart/QuickChart.java

xchart/src/main/java/com/xeiam/xchart/ScatterChart.java