Fix vega example

The segfault can't be reproduced in vtk 6.2.

A thorough debugging is necessary in order to find out why VTK is crashing in linux.

See merge request !44

Refactor renderCube and vegaFEM examples.

fixes #36

in order for the superbuild to work as designed.
Remove debugging from vtk objects.

Vtk rederer integration

See merge request !36

delegates.
The way render delegates need a bit of work.

Automating the way renderers are loaded.

Fix broken tests.
The renderCube example is broken now. Submitting patch soon.

Revert to build command in the Superbuild so that parallel
build work again.

Clean up and add static scene delegate.

If `SimMedTK_VTK_DIR` is defined, its value is used for `VTK_DIR`.
Otherwise, we ask CMake to find VTK and pass whatever it returns
from the superbuild to the SimMedTK build.

Documenting IO. Change name for IO delegates to match file name.

Capture by value in the IO delegator so that it remembers about the
delegate file name and IO pointer.

Fixing examples so they use the new IOs and renderer.

Add tests to IO. Move variables, types and implementation
of utility methods to IOMeshDelagates base class.

Commented out the VegaVoumetricMesh test until after I debug the meshIO.

until they are refactored.

Add reset function to base mash

in order to reset vertices to their original position.
Strip const from read function in the IOMeshDelegate and childs.
Move some utility functions to IOMeshDelegate.

corresponding simmedtk mesh structure.