Fixed in r22657
See http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=22657

Closing resolved issues that have not been updated in more than 3 months

See http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=23413

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COMP: Move most of find_package calls into each Slicer sub-project.

To help address issue 0003741 [1], call to find_package associated to CTK,
DCMTK, ITK and SlicerExecutionModel have been moved in every Slicer
sub project, library or module expecting it.

This allows to reduce both the number of include directories and
the number of libraries passed to the compiler.

Moving forward, every Slicer sub project, library or module will be
responsible to call find_package (optionally specifying a list of
components) and (if it applies) include the associated "use file".

Note that call to find_package(VTK) is still done at the top-level, before
moving the call to the expected sub-directories, the CTKConfig.cmake
will have to be updated to call find_package(VTK) specifying the required
components where it is needed.
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See http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=23412

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COMP: Disable VTK find_package/use_file_include in sub directory.

Calling "find_package(VTK)/include(${VTK_USE_FILE})" in both the top-level
directory and sub-directories is undefined. Indeed, If we include
VTK_USE_FILE (UseVTK.cmake) in the top level then it is probably adding
the autoinit definitions to the COMPILE_DEFINITIONS directory property.
Then that inherits to the sub-directory and could conflict with any such
property defined there. Thanks to Brad King for his insight.
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Fix committed to 2145-support-for-installing-extension-from-file branch.