added ability to set smooth parameter per series

lib/morris.line.coffee

@@ -219,6 +219,15 @@ class Morris.Line
   transY: (y) =>
     return @options.marginTop + @height - (y - @ymin) * @dy
 
+  # @private
+  shouldDrawSmooth: (series) =>
+    if typeof @options.smooth is 'boolean' && @options.smooth
+      true
+    else if typeof @options.smooth is 'object' and $.inArray(@seriesLabels[series], @options.smooth) > -1
+      true
+    else
+      false
+
   # Clear and redraw the chart.
   #
   # If you need to re-size your charts, call this method after changing the
@@ -288,7 +297,7 @@ class Morris.Line
     for i in [@seriesCoords.length-1..0]
       coords = $.map(@seriesCoords[i], (c) -> c)
       if coords.length > 1
-        path = @createPath coords, @options.marginTop, @left, @options.marginTop + @height, @left + @width
+        path = @createPath i, coords, @options.marginTop, @left, @options.marginTop + @height, @left + @width
         @r.path(path)
           .attr('stroke', @colorForSeries(i))
           .attr('stroke-width', @options.lineWidth)
@@ -307,9 +316,10 @@ class Morris.Line
   # create a path for a data series
   #
   # @private
-  createPath: (coords, top, left, bottom, right) ->
+  createPath: (series, coords, top, left, bottom, right) ->
     path = ""
-    if @options.smooth
+    
+    if @shouldDrawSmooth(series)
       grads = @gradients coords
       for i in [0..coords.length-1]
         c = coords[i]

morris.js

@@ -292,6 +292,8 @@
 
       this.updateHover = __bind(this.updateHover, this);
 
+      this.shouldDrawSmooth = __bind(this.shouldDrawSmooth, this);
+
       this.transY = __bind(this.transY, this);
 
       this.transX = __bind(this.transX, this);
@@ -554,6 +556,16 @@
       return this.options.marginTop + this.height - (y - this.ymin) * this.dy;
     };
 
+    Line.prototype.shouldDrawSmooth = function(series) {
+      if (typeof this.options.smooth === 'boolean' && this.options.smooth) {
+        return true;
+      } else if (typeof this.options.smooth === 'object' && $.inArray(this.seriesLabels[series], this.options.smooth) > -1) {
+        return true;
+      } else {
+        return false;
+      }
+    };
+
     Line.prototype.redraw = function() {
       this.r.clear();
       this.calc();
@@ -616,7 +628,7 @@
           return c;
         });
         if (coords.length > 1) {
-          path = this.createPath(coords, this.options.marginTop, this.left, this.options.marginTop + this.height, this.left + this.width);
+          path = this.createPath(i, coords, this.options.marginTop, this.left, this.options.marginTop + this.height, this.left + this.width);
           this.r.path(path).attr('stroke', this.colorForSeries(i)).attr('stroke-width', this.options.lineWidth);
         }
       }
@@ -649,10 +661,10 @@
       return _results;
     };
 
-    Line.prototype.createPath = function(coords, top, left, bottom, right) {
+    Line.prototype.createPath = function(series, coords, top, left, bottom, right) {
       var c, g, grads, i, ix, lc, lg, path, x1, x2, y1, y2, _i, _ref;
       path = "";
-      if (this.options.smooth) {
+      if (this.shouldDrawSmooth(series)) {
         grads = this.gradients(coords);
         for (i = _i = 0, _ref = coords.length - 1; 0 <= _ref ? _i <= _ref : _i >= _ref; i = 0 <= _ref ? ++_i : --_i) {
           c = coords[i];