Added "bar.space" parameter to set space between bars in bar charts. (Issue #1327)

src/config.js

@@ -163,6 +163,7 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         bar_width_ratio: 0.6,
         bar_width_max: undefined,
         bar_zerobased: true,
+        bar_space: 0,
         // area
         area_zerobased: true,
         // pie

src/shape.bar.js

@@ -91,14 +91,15 @@ c3_chart_internal_fn.generateGetBarPoints = function (barIndices, isSub) {
         axis = isSub ? $$.subXAxis : $$.xAxis,
         barTargetsNum = barIndices.__max__ + 1,
         barW = $$.getBarW(axis, barTargetsNum),
-        barX = $$.getShapeX(barW, barTargetsNum, barIndices, !!isSub),
+        barSpaceWidth = barW * $$.config.bar_space,
+        barX = $$.getShapeX(barW + barSpaceWidth, barTargetsNum, barIndices, !!isSub),
         barY = $$.getShapeY(!!isSub),
         barOffset = $$.getShapeOffset($$.isBarType, barIndices, !!isSub),
         yScale = isSub ? $$.getSubYScale : $$.getYScale;
     return function (d, i) {
         var y0 = yScale.call($$, d.id)(0),
             offset = barOffset(d, i) || y0, // offset is for stacked bar chart
-            posX = barX(d), posY = barY(d);
+            posX = barX(d) + barSpaceWidth / 2, posY = barY(d);
         // fix posY not to overflow opposite quadrant
         if ($$.config.axis_rotated) {
             if ((0 < d.value && posY < y0) || (d.value < 0 && y0 < posY)) { posY = y0; }