Added onPan/onZoom args (#178)

Pass chart to doPan() and doZoom()

Author: Techn1x

README.md

@@ -33,7 +33,7 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 		},
 		// Function called once panning is completed
 		// Useful for dynamic data loading
-		onPan: function() { console.log('I was panned!!!'); }
+		onPan: function({chart}) { console.log(`I was panned!!!`); }
 	},
 
 	// Container for zoom options
@@ -66,7 +66,7 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 		},
 		// Function called once zooming is completed
 		// Useful for dynamic data loading
-		onZoom: function() { console.log('I was zoomed!!!'); }
+		onZoom: function({chart}) { console.log(`I was zoomed!!!`); }
 	}
 }
 ```

src/plugin.js

@@ -200,7 +200,7 @@ function doZoom(chart, percentZoomX, percentZoomY, focalPoint, whichAxes) {
 		chart.update(0);
 
 		if (typeof zoomOptions.onZoom === 'function') {
-			zoomOptions.onZoom();
+			zoomOptions.onZoom({chart: chart});
 		}
 	}
 }
@@ -278,7 +278,7 @@ function doPan(chartInstance, deltaX, deltaY) {
 		chartInstance.update(0);
 
 		if (typeof panOptions.onPan === 'function') {
-			panOptions.onPan();
+			panOptions.onPan({chart: chartInstance});
 		}
 	}
 }