Add initial typescript definition file for google.visualization.

This is an initial d.ts for the google.visualization API, and is by no
means complete. It contains classes, interfaces, and functions for:

1. Loading visualization packages, and handling package load callbacks.
2. DataTable construction, manipulation, and creation from arrays.
3. Adding event listeners (minimal API, only 1 listener function def).
4. GeoChart construction & drawing.

A small tests file has also been added.

google.visualization/google.visualization-tests.ts

@@ -0,0 +1,41 @@
+/// <reference path="google.visualization.d.ts" />
+
+function test_arrayToDataTable() {
+    var array = [
+        ['City', 'Population', 'Area'],
+        ['Rome', 2761477, 1285.31],
+        ['Milan', 1324110, 181.76],
+        ['Naples', 959574, 117.27],
+        ['Turin', 907563, 130.17],
+        ['Palermo', 655875, 158.9],
+        ['Genoa', 607906, 243.60],
+        ['Bologna', 380181, 140.7],
+        ['Florence', 371282, 102.41],
+        ['Fiumicino', 67370, 213.44],
+        ['Anzio', 52192, 43.43],
+        ['Ciampino', 38262, 11],
+    ];
+
+    var dataTable = google.visualization.arrayToDataTable(array);
+}
+
+function test_ctorDataTable() {
+    var dataTable = new google.visualization.DataTable();
+    return dataTable;
+}
+
+function test_dataTableAddColumn() {
+    var dataTable = test_ctorDataTable();
+    dataTable.addColumn('string', 'First Column');
+    dataTable.addColumn('number', 'Second Column');
+}
+
+function test_dataTableAddRow() {
+    var dataTable = test_ctorDataTable();
+    dataTable.addRow(['row1', 6]);
+    dataTable.addRow(['row2', -1]);
+    dataTable.addRow(['row3', 0]);
+}
+
+
+