[vtkusers] FindVTK.cmake

[Brad King]

Hello, all:

The current CVS version of CMake contains a completely new implementation
of the FindVTK.cmake module.  While CMakeLists.txt files of user projects
that include this module need not be changed, the behavior is different
when CMake runs.

Previously, there were 4 cmake cache entries that the user potentially had
to set when running CMake:

VTK_BINARY_PATH, USE_BUILT_VTK
VTK_INSTALL_PATH, USE_INSTALLED_VTK

The new module requires only one cache entry to be set:

VTK_DIR - The directory containing VTKConfig.cmake
          (or UseVTK.cmake for VTK 4.0).

This will work for both a built and an installed VTK.  If using a built
VTK, just set VTK_DIR to where you used to set VTK_BINARY_PATH.  If using
an intalled VTK, set VTK_DIR to PREFIX/lib/vtk, or PREFIX/include/vtk for
VTK 4.0 (where PREFIX is the install prefix for VTK, such as /usr/local).

Note that if you are using a CMake 1.4.x release, you will not see this
change.  Keep it in mind for when you upgrade to a future release of CMake
1.6.

-Brad