Made the printextent-example backwards compatible

Added the mixin dynamically, corresponding to the ExtJS-Version.
Optimization of inclusion method for ExtJS libs

Used the changes from ca80980049e625021e7365cb69646fa567b83eb2 and
made some further enhancments.

The examples can now be loaded with the url param "extjs" to run either
with 4.2.1 or 5.0.1 (maybe some other versions will work to). Default
version is 5.0.1 if no param is passed.

For example:

foo/geoext2/examples/zoomslider/zoomslider.html?extjs=4.2.1

Some themes are only available in ExtJS4 (acces) or ExtJS5 (crisp/
crisp-touch/neptune-touch). So i made the options-toolbar (theme chooser)
react on the param, too.

The include-ext.js also works with the tests and so i'm going to change
the inclusion-method for these in an upcoming commit.

Some minor changes to code-indentation or removale of dangling
whitespaces are also inculded.
Using the new lib-inclusion method for the tests

Basically this commit includes codechanges to get the tests running with the
inclusion method from ca80980049e625021e7365cb69646fa567b83eb2.
This includes changes in all the tests and the setup of the testsuite in
tests/Test.AnotherWay.js.

Additonally some sourcecode is modified to get more tests runnning with
ExtJS5.0.1:

- this.model = 'foo.bar' is replace with this.setModel('foo.bar')
- bind an unbind functions in selection/FeatureModel.js are renamed according
  to 3887196b47126440f3256fd26a182dd5232b337d
- some commits are work in progress but maybe someone can benefit from these
  tests failing with ExtJS5.0.1:
  - Form.html
  - data/proxy/Protocol.hmtl
  - data/reader/Attribute.html
  - data/reader/WfsCapabilities.html
  - data/reader/Wmc.html
  - data/reader/WmsCapabilities.html
  - data/reader/WmsDescribeLayer.html
  - form/action/Search.html
  - form/Basic.html
  - panel/map.html
  - selection/FeatureModel.html
  - tree/LayerContainer.html