COMP: Fix CMake 3.x warnings related to CMP0054 and CMP0026

* Update ExternalProjectDependency based on commontk/Artichoke@6725b6a

* This commit fixes warning like these ones:

// ----------------------
CMake Warning (dev) at CMake/ctkMacroCheckExternalProjectDependency.cmake:345 (if):
  Policy CMP0054 is not set: Only interpret if() arguments as variables or
  keywords when unquoted.  Run "cmake --help-policy CMP0054" for policy
  details.  Use the cmake_policy command to set the policy and suppress this
  warning.

  Quoted variables like "SB_SECOND_PASS" will no longer be dereferenced when
  the policy is set to NEW.  Since the policy is not set the OLD behavior
  will be used.
Call Stack (most recent call first):
  CMake/ctkMacroCheckExternalProjectDependency.cmake:596 (ExternalProject_Message)
  CMakeExternals/Log4Qt.cmake:9 (ExternalProject_Include_Dependencies)
  CMake/ctkMacroCheckExternalProjectDependency.cmake:568 (include)
  CMake/ctkMacroCheckExternalProjectDependency.cmake:614 (ExternalProject_Include_Dependencies)
  CMake/ctkBlockCheckDependencies.cmake:132 (ExternalProject_Include_Dependencies)
  CMakeLists.txt:970 (include)
// ----------------------

// ----------------------
1>-- Configuring Loadable module: Transforms [qSlicerTransformsModuleExport.h]
1>CMake Warning (dev) at C:/D/P/SonoEQ-0-build/Slicer-build/CTK/CMake/ctkMacroBuildQtPlugin.cmake:168 (get_target_property):
1>  Policy CMP0026 is not set: Disallow use of the LOCATION target property.
1>  Run "cmake --help-policy CMP0026" for policy details.  Use the cmake_policy
1>  command to set the policy and suppress this warning.
1>  The LOCATION property should not be read from target
1>  "qSlicerAnnotationsModuleWidgetsPlugins".  Use the target name directly
1>  with add_custom_command, or use the generator expression $<TARGET_FILE>, as
1>  appropriate.
1>Call Stack (most recent call first):
1>  C:/D/P/SonoEQ-0-build/Slicer-build/CTK/CMake/ctkMacroBuildQtPlugin.cmake:181 (ctkMacroBuildQtPlugin)
1>  Modules/Loadable/Annotations/Widgets/DesignerPlugins/CMakeLists.txt:36 (ctkMacroBuildQtDesignerPlugin)
// ----------------------


* Updates of the associated projects are reported below:

[Artichoke]
$ git shortlog c3eb170..6725b6a
Jean-Christophe Fillion-Robin (12):
      Rename Artichoke into ExternalProjectDependency
      Add cmake sphinx extension based on Kitware/CMake@3c8226e59
      Add explicit support for function and macro directive
      Add sphinx gitignore
      Add sphinx documentation
      Convert README into rst and reference it from index.rst
      Include "indices and tables" only if generating html
      Add docs badge
      Merge pull request #8 from mwoehlke-kitware/installable-external-projects
      Fix tests including the correct module (broken after commit 9106d3d)
      Tweak test in ExternalProject_Message to avoid warning related to CMP0054
      Update tests setting policy CMP0054 to OLD.

Matthew Woehlke (1):
      Add function to install external CMake projects

[CTK]
$ git shortlog 1c97e54..6dfdb85 --no-merges
Andreas Fetzer (1):
      Remove empty build command and set install command empty. Thus is cannot happen     that the dcmtk libraries are installed to some unintended location.     Setting dcmtk_dir to dcmtk-build directory

Christian Askeland (4):
      fixed crashing line in ctkFileDialog for Qt5.
      improved in-code description of previous ctkFileDialog crash fix
      Fixed broken doxygen generation for Plugin Framework
      set doxygen variable ensuring macro definitions of type MY_FOO(arg) dont mess up doc generation

Jean-Christophe Fillion-Robin (2):
      Update ExternalProjectDependency based on commontk/Artichoke@388fc33
      Update ctkMacroBuildQtPlugin to fix CMake warning related to CMP0026

Sascha Zelzer (1):
      Removed custom QT5_INSTALL_PREFIX variable.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23800 3bd1e089-480b-0410-8dfb-8563597acbee