Distribute FindFoo.cmake files

In the build tree into: `PROJECT_BINARY_DIR/Modules`
In install tree into `DGTAL_CMAKE_DIR_INSTALL/Modules`

Also change find_dependency to find_package for the FindFoo.cmake packages.
It seems that find_dependency prioritizes Config files and ignore
Find modules.

cmake/DGtalConfig.cmake.in

@@ -10,6 +10,9 @@ set(DGTAL_VERSION "@DGTAL_VERSION@")
 
 include(CMakeFindDependencyMacro)
 
+get_filename_component(DGTAL_CMAKE_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${DGTAL_CMAKE_DIR}/Modules")
+
 #### Required dependencies  ####
 find_dependency(Boost REQUIRED
   @Boost_HINTS@
@@ -19,14 +22,14 @@ find_dependency(ZLIB REQUIRED
   )
 
 if(@GMP_FOUND_DGTAL@) #if GMP_FOUND_DGTAL
-  find_dependency(GMP REQUIRED
+  find_package(GMP REQUIRED
     @GMP_HINTS@
     )
   set(WITH_GMP 1)
 endif()
 
 if(@MAGICK++_FOUND_DGTAL@) #if MAGICK++_FOUND_DGTAL
-  find_dependency(Magick REQUIRED
+  find_package(Magick REQUIRED
     @Magick_HINTS@
     )
   set(WITH_MAGICK 1)
@@ -40,7 +43,7 @@ if(@ITK_FOUND_DGTAL@) #if ITK_FOUND_DGTAL
 endif()
 
 if(@CAIRO_FOUND_DGTAL@) #if CAIRO_FOUND_DGTAL
-  find_dependency(Cairo REQUIRED
+  find_package(Cairo REQUIRED
     @Cairo_HINTS@
     )
   set(WITH_CAIRO 1)
@@ -54,7 +57,7 @@ if(@HDF5_FOUND_DGTAL@) #if HDF5_FOUND_DGTAL
 endif()
 
 if (@QGLVIEWER_FOUND_DGTAL@) #if QGLVIEWER_FOUND_DGTAL
-  find_dependency(QGLVIEWER REQUIRED
+  find_package(QGLVIEWER REQUIRED
     @QGLVIEWER_HINTS@
     )
   set(WITH_VISU3D_QGLVIEWER 1)
@@ -106,13 +109,12 @@ if(@CGAL_FOUND_DGTAL@) #if CGAL_FOUND_DGTAL
 endif()
 
 if(@FFTW3_FOUND_DGTAL@) #if FFTW3_FOUND_DGTAL
-  find_dependency(FFTW3 REQUIRED
+  find_package(FFTW3 REQUIRED
     @FFTW3_HINTS@
     )
   set(WITH_FFTW3 1)
 endif()
 
-get_filename_component(DGTAL_CMAKE_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
 if(NOT TARGET DGtal)
   # Our imported targets, including dependencies
   include ("${DGTAL_CMAKE_DIR}/DGtalLibraryDepends.cmake")

cmake/DGtalConfigGenerator.cmake

@@ -49,3 +49,16 @@ install(FILES
   "${PROJECT_BINARY_DIR}/InstallFiles/DGtalConfig.cmake"
   "${PROJECT_BINARY_DIR}/InstallFiles/DGtalConfigVersion.cmake"
   DESTINATION "${DGTAL_CMAKE_DIR_INSTALL}" COMPONENT dev)
+
+# Distribute FindFoo.cmake files to the build and install tree
+set(_find_cmake_files
+  "${PROJECT_SOURCE_DIR}/cmake/FindCairo.cmake"
+  "${PROJECT_SOURCE_DIR}/cmake/FindFFTW3.cmake"
+  "${PROJECT_SOURCE_DIR}/cmake/FindMagick.cmake"
+  "${PROJECT_SOURCE_DIR}/cmake/FindQGLVIEWER.cmake"
+  "${PROJECT_SOURCE_DIR}/cmake/FindGMP.cmake"
+  )
+file(COPY ${_find_cmake_files}
+  DESTINATION "${PROJECT_BINARY_DIR}/Modules")
+install(FILES ${_find_cmake_files}
+  DESTINATION "${DGTAL_CMAKE_DIR_INSTALL}/Modules" COMPONENT dev)