tweak karma graph output for many data points

if there's a ton of data points, the graph starts looking real gross,
so do a couple things to make the display of that a bit simpler so
there's less noise and distracting lines and whatnot

dr_botzo/karma/templates/karma/karma_key.html

@@ -13,6 +13,17 @@
   <script type="text/javascript">
     Chart.defaults.global.responsive = true;
     Chart.defaults.global.maintainAspectRatio = true;
+    Chart.types.Line.extend({name : "AltLine",
+      initialize : function(data) {
+        Chart.types.Line.prototype.initialize.apply(this, arguments);
+        this.scale.draw = function() {
+           if (this.display && (this.xLabelRotation > 90)) {
+              this.endPoint = this.height - 5;
+           }
+           Chart.Scale.prototype.draw.apply(this, arguments);
+        };
+      }
+    });
     var ctx = $("#karma_history").get(0).getContext("2d");
     var data = {
       labels: ["EPOCH", {% for x in entry.history %}"{{ x.0 }}", {% endfor %}],
@@ -29,8 +40,13 @@
         }
       ]
     };
-    var myLineChart = new Chart(ctx).Line(data, {
-      pointDot: false
+    var myLineChart = new Chart(ctx).AltLine(data, {
+      pointDot: false,
+      {% if entry.history|length > 100 %}
+        showTooltips: false,
+        scaleShowVerticalLines: false,
+      {% endif %}
+      tooltipEvents: ["click"]
     });
   </script>
 {% endblock %}