playing around with number formatting

...n/java/com/xeiam/xchart/demo/charts/date/DateChart03.java

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

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

...xchart/internal/chartpart/AxisTickBarChartCalculator.java

...art/internal/chartpart/AxisTickLogarithmicCalculator.java

...chart/internal/chartpart/AxisTickNumericalCalculator.java

...va/com/xeiam/xchart/internal/chartpart/DateFormatter.java

.../com/xeiam/xchart/internal/chartpart/NumberFormatter.java

...t/src/test/java/com/xeiam/xchart/NumberFormatterTest.java

.../src/test/java/com/xeiam/xchart/NumberFormatterTest2.java