vtkModuleRemote: Report download progress

This is particularly useful to provide feedback while downloading
larger project like VTKExamples.

CMake/vtkModuleRemote.cmake

 # Function to fetch remote modules.
 
 # Helper to perform the initial git clone and checkout.
-function(_git_clone git_executable git_repository git_tag module_dir)
+function(_git_clone git_executable git_repository git_tag module_dir git_progress)
+
+  set(git_clone_options)
+  if(git_progress)
+    list(APPEND git_clone_options --progress)
+  endif()
+
   execute_process(
-    COMMAND "${git_executable}" clone "${git_repository}" "${module_dir}"
+    COMMAND "${git_executable}" clone ${git_clone_options} "${git_repository}" "${module_dir}"
     RESULT_VARIABLE error_code
-    OUTPUT_QUIET
-    ERROR_VARIABLE git_clone_error
     )
   if(error_code)
-    message(FATAL_ERROR "Failed to clone repository: '${git_repository}' Clone error is: '${git_clone_error}'")
+    message(FATAL_ERROR "Failed to clone repository: '${git_repository}'")
   Endif()
 
   execute_process(
@@ -97,14 +101,14 @@ endfunction()
 
 # Helper function to fetch a module stored in a Git repository.
 # Git fetches are only performed when required.
-function(_fetch_with_git git_executable git_repository git_tag module_dir)
+function(_fetch_with_git git_executable git_repository git_tag module_dir git_progress)
   if("${git_tag}" STREQUAL "" OR "${git_repository}" STREQUAL "")
     message(FATAL_ERROR "Tag or repository for git checkout should not be empty.")
   endif()
 
   # If we don't have a clone yet.
   if(NOT EXISTS "${module_dir}")
-    _git_clone("${git_executable}" "${git_repository}" "${git_tag}" "${module_dir}")
+    _git_clone("${git_executable}" "${git_repository}" "${git_tag}" "${module_dir}" "${git_progress}")
     message(STATUS " The remote module: ${git_repository} is cloned into the directory ${module_dir}")
   else() # We already have a clone, but we need to check that it has the right revision.
     _git_update("${git_executable}" "${git_repository}" "${git_tag}" "${module_dir}")
@@ -150,12 +154,14 @@ function(vtk_fetch_module _name _description)
     if("${_version}" VERSION_LESS 1.6.6)
       message(FATAL_ERROR "Git version 1.6.6 or later is required.")
     endif()
+    set(git_progress 1)
     set(_msg "Fetching remote module: ${_name}")
     message(STATUS "${_msg}")
     _fetch_with_git("${GIT_EXECUTABLE}"
       "${_fetch_options_GIT_REPOSITORY}"
       "${_fetch_options_GIT_TAG}"
       "${VTK_SOURCE_DIR}/Remote/${_name}"
+      "${git_progress}"
       )
     message(STATUS "${_msg} - done")
   endif()