WIP: Integrating msvVTKButtons to the clustering interface.

Issue #54
Merge branch '54-use-msvVTKButtons-in-ButtonClusters_tmp' into 54-use-msvVTKButtons-in-ButtonClusters

Conflicts:
	Applications/ButtonClusters/msvQButtonClustersMainWindow.cxx
	Libs/VTK/Widgets/msvVTKWidgetClusters.cxx
	Libs/VTK/Widgets/msvVTKWidgetClusters.h

Issue #54
WIP: Adding msvVTKButtons support in button clustering

Issue #54
WIP: Adding msvVTKButtons support

Issue #54
WIP: Add cluster visualization and cleaned GUI a bit.

Issue #54
WIP: Adding cluster representation to display clustering using a graph

Issue #54
Add multiple improvements.

Closes #54
Add preliminary support for msvVTKButtons. Immprovements to the GUI.
Fix unistd compilation error with VisualStudio
Use CTK utility functions to convert vtkImage to QImage

On windows, there was random crashes in getPreview when the qimage was
going out of scope.
Fix compilation warnings by using vtkIdType instead of size_t

vtkIdType is the VTK preferred unsigned type.
Copy icon.png to build and install directory
Don't show the volume corners

It adds more buttons that makes the demo confusing.
Support sub-subdirectory for loading data

by making the readData method recursive.
Don't refresh the view unnecessarilly when toggling data visibility

By calling updateView() in showData(), it was triggering a rendering
2*n times.
Show VTKButtons on interaction

* msvVTKButtons::Update() must be called to refresh their visibility and
positions.
* Don't trigger a rendering each time 1 button is modified, refreshes
should be triggered by the application.
* Factorize the ShowButtons()/HideButtons()
Fix crash on uninitialized variables
Merge branch '54-use-msvVTKButtons-in-ButtonClusters' into ButtonClustering

# By Julien Finet (41) and others
# Via Richard Christie (20) and others
* 54-use-msvVTKButtons-in-ButtonClusters: (105 commits)
  Fix crash on uninitialized variables
  Show VTKButtons on interaction
  Don't refresh the view unnecessarilly when toggling data visibility
  Support sub-subdirectory for loading data
  Don't show the volume corners
  Copy icon.png to build and install directory
  Fix compilation warnings by using vtkIdType instead of size_t
  Use CTK utility functions to convert vtkImage to QImage
  Fix unistd compilation error with VisualStudio
  Add multiple improvements.
  WIP: Adding cluster representation to display clustering using a graph
  WIP: Add cluster visualization and cleaned GUI a bit.
  WIP: Adding msvVTKButtons support
  WIP: Adding msvVTKButtons support in button clustering
  The demo now takes any data directory and loads all containing files.
  WIP: Integrating msvVTKButtons to the clustering interface.
  Fix VTK based documentation
  Fix msvQTimePlayerWidget documentation.
  Add documentation for msvVTKButtons
  Expand vtk macros such as vtkSetMacro...
  ...
Merge branch 'ButtonClustering'

# By Julien Finet (9) and Ricardo Ortiz (6)
# Via Julien Finet (2) and Ricardo Ortiz (1)
* ButtonClustering:
  Fix crash on uninitialized variables
  Show VTKButtons on interaction
  Don't refresh the view unnecessarilly when toggling data visibility
  Support sub-subdirectory for loading data
  Don't show the volume corners
  Copy icon.png to build and install directory
  Fix compilation warnings by using vtkIdType instead of size_t
  Use CTK utility functions to convert vtkImage to QImage
  Fix unistd compilation error with VisualStudio
  Add multiple improvements.
  WIP: Adding cluster representation to display clustering using a graph
  WIP: Add cluster visualization and cleaned GUI a bit.
  WIP: Adding msvVTKButtons support
  WIP: Adding msvVTKButtons support in button clustering
  WIP: Integrating msvVTKButtons to the clustering interface.

Conflicts:
	Applications/ButtonClusters/msvQButtonClustersMainWindow.cxx
	Libs/VTK/Widgets/msvVTKButtonsManager.cxx
	Libs/VTK/Widgets/msvVTKButtonsManager.h
	Libs/VTK/Widgets/msvVTKWidgetClusters.cxx
	Libs/VTK/Widgets/msvVTKWidgetClusters.h