Add a mappanel test originally from #61.

The test form @lellmer is ported over, the fix introduced in that particular
pull request is no longer needed.
Fix a few typos in the documentation.
Merge pull request #198 from jomue/doc-improvements

Fix a few typos in the documentation.
API docs for code example improved.
Fix API docs.
Change copyright to 2013.
Merge pull request #199 from marcjansen/2013

Change copyright to 2013.
Smaller enhancements to the docs.
Merge pull request #200 from marcjansen/docdocdoc

Smaller enhancements to the docs.
Set GeoExt.version to 2.0.0.
Refactor namespace and version setup.
Add a test to verify namespace/version-setup.
Require namespace/version class where needed.
Merge pull request #201 from marcjansen/version

Refactor namespace and version setup
use theme chooser in all examples
in order for people to extend the GeoExt.data.LayerModel, we need to use inheritableStatics for the static function and we need to make sure that inside of the static function createFromLayer we access a static function i.e. getProxy instead of the member proxy
Merge pull request #203 from bartvde/layermodel

in order for people to extend the GeoExt.data.LayerModel, we need to use... (r=@juliensam)
minor update to the README
Add and use a base class for mappanel sliders.

This reduces the amount of copied code and reuses the methods from the
base class.
Merge pull request #204 from marcjansen/refactor-slider

Add and use a base class for mappanel sliders. (r=@bartvde)