Create new branch 'model-view-devel'
Initial version of ModelIndex
Fix typo
Cleanup ModelIndex class

- according to code guideliness
- remove the `isValid` method as it will
be moved to the ItemModel
Add the ItemModel interface
Remove row and column from ModelIndex

With this, we make it dumber and allow the model
to fully control what info is relevant to it.
Add the initial ItemDataRole enumeration
Replace getImage/getString with getData & data role
Replace row/column with parent/child relation
Add the initial ListView files and ItemView base class

This will be used as base class for all future views.
Also add the "views" subdirectory into the cmake script
Add initial ModelView sample files
Add set/getModel to ItemModel
Make ItemView inherit from Window
Create the initial ListView class
Rename 'getChildrenCount' to 'getChildCount'
Rename _CEGUIAll_h_ define to _CEGUIAllWidgets_h_

Do this to allow other "all.h" definitions.
Add ListView window factory type.
Add the ListView window renderer
Add ListView to the already existing schemes

At least for now, the actual rendering will be done like the ListBox.
Add an empty ListView to the samples.