misc fixes on demoCharts app

...ain/java/com/xeiam/xchart/demo/charts/bar/BarChart05.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart01.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart02.java

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

...n/java/com/xeiam/xchart/demo/charts/date/DateChart04.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart05.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart06.java

...n/java/com/xeiam/xchart/demo/charts/date/DateChart07.java

.../com/xeiam/xchart/demo/charts/scatter/ScatterChart03.java

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

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

...c/main/java/com/xeiam/xchart/internal/chartpart/Axis.java

...in/java/com/xeiam/xchart/internal/chartpart/AxisPair.java

.../xeiam/xchart/internal/chartpart/PlotContentBarChart.java

...rnal/chartpart/axistickcalculator/AxisTickCalculator.java

...rtpart/axistickcalculator/BarChartAxisTickCalculator.java

.../chartpart/axistickcalculator/DateAxisTickCalculator.java

.../internal/chartpart/axistickcalculator/DateFormatter.java