chore(project-template): warn about add_dependency use

cmake/add_dependency.cmake

@@ -54,7 +54,7 @@ FUNCTION(add_dependency dependency_project_name required_version)
 ENDFUNCTION(add_dependency)
 
 # make sure that cmake finds modules provided by project-template.
-# since with new cmake concept for imported targets, dependencies also search for implicit dependencies, 
+# since with new cmake concept for imported targets, dependencies also search for implicit dependencies,
 # all projects using add_dependency also require this module path.
 set(_projectTemplateModulePath ${CMAKE_SOURCE_DIR}/cmake/Modules)
 # substr search is better than regex if paths have special characters
@@ -62,3 +62,11 @@ string(FIND ":${CMAKE_MODULE_PATH}:" ":${_projectTemplateModulePath}:" _projectT
 if (${_projectTemplateModulePathPos} EQUAL -1)
     list(APPEND CMAKE_MODULE_PATH "${_projectTemplateModulePath}")
 endif()
+
+message(WARNING "
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+You are using add_dependency() in your CMakeLists.txt which is deprecated and may lead to subtle problems. Please follow the project-template migration guide to cmake imported targets.
+Furhter processing is delayed by 5 seconds.
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+")
+execute_process(COMMAND ${CMAKE_COMMAND} -E sleep 5.0)