The new vtk module system required changes to
vtkModuleRemote.cmake. The old system used a cmake option,
Build_modulename:BOOL ON/OFF to enable a remote module. The new module
system uses a cmake variable, VTK_MODULE_ENABLE_VTK with values YES,
WANT, DONT_WANT, NO and DEFAULT.

Also, CMakeLists.txt now includes add_subdirectory(Remote) and the Remote directory is added to vtk_source_directories.

To test the new remote macros, we enabled three remote modules:
PoissonReconstruction, Powercrust and SplineDrivenImageSlicer.

The WikiExamples are no longer available as a remote module. They will instead be added as an external project in the future, WikiExamples.remote.cmake has been removed.