make sure labels for cumulative distribution don't overlap

pdb-plotting/src/main/java/org/lucares/pdb/plot/api/CumulativeDistributionHandler.java

@@ -38,12 +38,24 @@ public class CumulativeDistributionHandler implements AggregateHandler {
     result.setType(Type.Number);
     result.setAxis(GnuplotAxis.X2); // TODO determine automatically
     result.setFormat("%.0f%%");
-    result.setTicIncrement(5);
+    result.setTicIncrement(computeTicIncrement(settings));
     result.setFrom("0");
     result.setTo("100");
     return result;
   }
 
+  private int computeTicIncrement(GnuplotSettings settings) {
+    int widthByFontSize = settings.getWidth()/GnuplotSettings.TICKS_FONT_SIZE;
+    if (widthByFontSize < 50) {
+      return 20;
+    }
+    else if (widthByFontSize < 75) {
+      return 10;
+    }else {
+      return 5;
+    }
+  }
+
   @Override
   public void addPlot(StringBuilder result, AggregatedData aggregatedData, LineStyle lineStyle, Optional<String> title) {
     appendfln(result, "'%s' using 1:2 %s with lines axes x2y1 lw 2 %s, \\", //