cleaned up constructors

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

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

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

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

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

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

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

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

src/main/java/com/xeiam/xchart/series/SeriesMarker.java