Prevent beginning of title from being clipped when title is centereed

src/title.js

@@ -15,7 +15,7 @@ c3_chart_internal_fn.xForTitle = function () {
     if (position.indexOf('right') >= 0) {
         x = $$.currentWidth - $$.getTextRect($$.title.node().textContent, $$.CLASS.title, $$.title.node()).width - config.title_padding.right;
     } else if (position.indexOf('center') >= 0) {
-        x = ($$.currentWidth - $$.getTextRect($$.title.node().textContent, $$.CLASS.title, $$.title.node()).width) / 2;
+        x = Math.max(($$.currentWidth - $$.getTextRect($$.title.node().textContent, $$.CLASS.title, $$.title.node()).width) / 2, 0);
     } else { // left
         x = config.title_padding.left;
     }