FIX: Bug #2 (Exception when creating stats) - Added check to ensure y-axis increment > 0 in Graph.lineChart to avoid specific exception (org.jCharts.properties.PropertyException ("The Axis Increment can not be a negative value or zero.")), an increment < 1 arising when the difference between the min and max file counts is less than 4. Renamed related Graph.lineChart parameters and added a comment for clarity. The y-axis increment is just that - an increment, not necessarily an increase.
