Split the zoomMinMax method into three parts (creating the minAndMaxAreInvalid and setDomainRangeCharts methods).
Created ZOOM_IN_COMMAND, ZOOM_ORIGINAL_COMMAND and ZOOM_OUT_COMMAND constants for handling these zoom commands (which solves some Checkstyle issues).
Created DIMENSION_5X0, DIMENSION_10X0 and DIMENSION_0X10 constants for GUI layout.
Created ZOOM_X_AXIS_DEFAULT_START and ZOOM_X_AXIS_DEFAULT_END constants for zooming along the x axis.
Created CHART_FRAME_TITLE_PREFIX constant used for titles of the chart frames.
Added punctuation for Javadoc comments (JavadocStyle, see http://checkstyle.sourceforge.net/config_javadoc.html).
Put some trailing comments on a separate line (TrailingComment, see http://checkstyle.sourceforge.net/config_misc.html).
Merge pull request #16 from FreekDB/master

Yet another group of Checkstyle fixes