Use recent versions of the base libraries in the testsuite

Change the tests so that they work with OpenLayers 2.13 and ExtJS 4.2.1.

All tests pass in Chrome.

Firefox has the following errors:

```
  * container/VectorLegend.html: fail 1 ok 6 (detailed: fail 1 ok 36)
    * test_saferemove fail 1 ok 2
      * fail zoomend handler disconnected
  * panel/Map.html: fail 1 ok 10 (detailed: fail 0 ok 60)
    * test_add planned 1 assertions but got 0; fail 0 ok 0
      * exception: : object: me.el is null
  * selection/FeatureModel.html: fail 1 ok 3 (detailed: fail 1 ok 30)  
    * test_autopan_map_on_selection fail 1 ok 3
      * fail Map' s zoom has changed in order to make multiple selected features visible.
  * slider/Zoom.html: fail 1 ok 1 (detailed: fail 2 ok 7)
    * test_zoomslider fail 2 ok 5
      * fail slider has correct value after zoomIn. eq: values differ: got 2, but expected 3
      * fail slider has correct value after zoomTo. eq: values differ: got 2, but expected 0
  * window/Popup.html: fail 1 ok 11 (detailed: fail 3 ok 47)
    * test_anchorPopup fail 3 ok 2
      * fail anchored popup moves once on collapse. eq: values differ: got 0, but expected 1
      * fail anchored popup moves once on expand. eq: values differ: got 0, but expected 1
      * fail anchored popup moves once on resize. eq: values differ: got 0, but expected 1
```

Internet Explorer has the following error (which also happens to be present in Firefox):

```
  * window/Popup.html: fail 1 ok 11 (detailed: fail 3 ok 47)
    * test_anchorPopup fail 3 ok 2
      * fail anchored popup moves once on collapse. eq: values differ: got 0, but expected 1
      * fail anchored popup moves once on expand. eq: values differ: got 0, but expected 1
      * fail anchored popup moves once on resize. eq: values differ: got 0, but expected 1
```

I am in favor of merging this regardless of the failures above and address these in separate pull requests. If others disagree, I am willing to keep this open and try to add commits that squash the remaining bugs.

Edit:

The popup error is addressed in [this branch of mine](https://github.com/marcjansen/geoext2/compare/tests-update-4.2.1...ie8-window?expand=1), which is based on top of this branch.