[CMake] Building ITK with VTK 5.6

[Mathieu Malaterre]

Hi there,

  I am trying to build ITK from a toplevel directory, my application
is setup simply like this:

$ cat CMakeLists.txt
project(MySuperApp)
find_package(VTK REQUIRED)
message("${VTK_VERSION}")
add_subdirectory(ITK) # contains the ITK source

Since cmake 2.8 find_package now sets VTK_VERSION which is used
internally in ITK to determine if MetaIO is being build from VTK or
ITK.
Could someone please:
- confirm VTK_VERSION now appears as 5.6.0 since the update to cmake
2.8 / vtk 5.6
- could someone please suggest the correct way to detect if metaio if
build from ITK or not.

Thanks a lot !