QmlMitkFourRenderWindowWidget and QmlMitkRenderWindowItem

Attempt to integrate MITK render windows into a QML scene.

This change brings two QtQuick items

 - QmlMitkRenderWindowItem as a mitk::RenderWindow variant
   based on Kitware's OpenView component QVTKQuickItem.

 - QmlMitkFourRenderWindowWidget as a replacement for QmitkStdMultiWidget
   with much reduced functionality

Most things are working nicely now, major issues to solve:

 - Qt Quick renders in a second thread, which collides with
   some things in MITK. This demo brings only a workaround
   and not a solution.. See QmlMitkBigRenderLock.

 - Events handled by QmlMitkRenderWindowItem are probably incomplete

 - QmlMitkFourRenderWindowWidget and QmlMitkRenderWindowItem
   need cleaned-up interfaces to be really usable for applications

 - The new modules must be nicely integrated in to the build system
   - find and use Qt5 optionally, make this a condition to QmlMitk
   - bring the minimal changes back to OpenView (pull-request submitted)
   - build OpenView as a package dependency
    - (patch OpenView if neccessary)
Introduce DESIRED_QT_VERSION and QT_MODULES

The MITK build can now depend on either Qt4 or Qt5.
Modules can list their dependencies towards specific
Qt modules via the QT_MODULES variable.

Conflicts:

	CMake/PackageDepends/MITK_Qt5_Config.cmake
Generate Qt5 module definitions
Add LICENSE and README to OpenView module, rename to OpenViewCore

(only the core directory has been imported to MITK)

Conflicts:

	Modules/OpenViewCore/CMakeLists.txt
Separate keywords QT4_MODULES and QT5_MODULES

Conflicts:

	CMake/mitkMacroCreateModule.cmake
Test module Qt4Qt5TestModule
Fixing Qt4 dependencies
Some base documentation for classes in QmlMitk
Merge commit '78619fb' into bug-16272-qt5-build-system
Support for specifying Qt4 modules as dependencies.
Require CMake 2.8.9 when using Qt5.
Build external projects depending on Qt version. Qwt now compiles with Qt5.
Introduced a new mitk_use_modules CMake function.

This CMake function takes a target and a list of dependencies (MITK
modules, packages, or Qt components) and sets up include directories,
linker dependencies, and compile flags for the specified target.

Conflicts:

	CMake/PackageDepends/Qt/MITK_Qt5_Config.cmake
	CMake/mitkMacroCreateModule.cmake
Undo deactivation of probably meaningful code
Set CMake policy CMP0020 NEW: Automatically link Qt executables to qtmain target on Windows
Adapt CTest interface to Visual Studio
Added ConnectTo Method
Updated Tutorial and Documentation for new ConnectTo Method
Avoid multiple includes of ITK targets.
Fixed Qt4 module names and include directories.