Improve tick culling: always leave last text shown

src/c3.axis.js

@@ -113,6 +113,16 @@ function c3_axis(d3, params, $$) {
 
         for(i = 0; i < l; i++){
             if(i % cullStep){
+                if(i === l-1){
+                    // Last rectangle should always be present, so if this is last but one rect
+                    // and last one should be culled, we remove this one instead of last
+                    var x = i-1;
+                    do {
+                        rects[x] = null;
+                        x--;
+                    } while(x > 0 && (rects[x] === null || hasIntersection(rects[i], rects[x])));
+                    break;
+                }
                 rects[i] = null;
             }
         }
@@ -360,8 +370,8 @@ function c3_axis(d3, params, $$) {
             var textClass = '.c3-axis-' + axisId + ' .tick';
             var textRects = text.data().map(function(data) {
                 var rect = $$.getTextRect(textFormatted(data), textClass);
-                // Smaal additional padding between texts
-                rect.width += 10;
+                // Small additional padding between texts
+                rect.width += 2;
                 return rect;
             });