fix a bug of layer changes.

see :http://code.google.com/p/svg-edit/issues/detail?id=1099

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2516 eee81c28-f429-11dd-99c0-75d572ba1ddd

editor/svg-editor.js

@@ -3673,6 +3673,7 @@
 			};
 
 			var populateLayers = function() {
+        svgCanvas.clearSelection();
 				var layerlist = $('#layerlist tbody').empty();
 				var selLayerNames = $('#selLayerNames').empty();
 				var drawing = svgCanvas.getCurrentDrawing();