show legend for gauges which have more than one arc

src/core.js

@@ -221,7 +221,7 @@ c3_chart_internal_fn.initWithData = function (data) {
     }
 
     // when gauge, hide legend // TODO: fix
-    if ($$.hasType('gauge')) {
+    if ($$.hasType('gauge') && $$.config.data_columns.length <= 1) {
         config.legend_show = false;
     }
 

src/legend.js

@@ -307,7 +307,9 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
     tiles = $$.legend.selectAll('line.' + CLASS.legendItemTile)
             .data(targetIds);
         (withTransition ? tiles.transition() : tiles)
-            .style('stroke', $$.color)
+            .style('stroke', $$.levelColor ? function(id) {
+                return $$.levelColor($$.cache[id].values[0].value);
+            } : $$.color)
             .attr('x1', x1ForLegendTile)
             .attr('y1', yForLegendTile)
             .attr('x2', x2ForLegendTile)