Cycle lineColors (#78)

Fixes crashes when number of series is larger than number of line colors.

lib/morris.line.coffee

@@ -283,7 +283,7 @@ class Morris.Line
       if coords.length > 1
         path = @createPath coords, @options.marginTop, @left, @options.marginTop + @height, @left + @width
         @r.path(path)
-          .attr('stroke', @options.lineColors[i])
+          .attr('stroke', @colorForSeries(i))
           .attr('stroke-width', @options.lineWidth)
     @seriesPoints = ([] for i in [0..@seriesCoords.length-1])
     for i in [@seriesCoords.length-1..0]
@@ -292,7 +292,7 @@ class Morris.Line
           circle = null
         else
           circle = @r.circle(c.x, c.y, @options.pointSize)
-            .attr('fill', @options.lineColors[i])
+            .attr('fill', @colorForSeries(i))
             .attr('stroke-width', 1)
             .attr('stroke', '#ffffff')
         @seriesPoints[i].push(circle)
@@ -355,7 +355,7 @@ class Morris.Line
     @yLabels = []
     for i in [0..@series.length-1]
       yLabel = @r.text(0, @options.hoverFontSize * 1.5 * (i + 1.5) - @hoverHeight / 2, '')
-        .attr('fill', @options.lineColors[i])
+        .attr('fill', @colorForSeries(i))
         .attr('font-size', @options.hoverFontSize)
       @yLabels.push(yLabel)
       @hoverSet.push(yLabel)
@@ -423,6 +423,10 @@ class Morris.Line
   yLabelFormat: (label) ->
     "#{@options.preUnits}#{Morris.commas(label)}#{@options.postUnits}"
 
+  # @private
+  colorForSeries: (index) ->
+    @options.lineColors[index % @options.lineColors.length]
+
 
 # Parse a date into a javascript timestamp
 #