everything works, make now runs doxygen once and only once, after all

the required files have been generated.

doc/examples/CMakeLists.txt

@@ -1,5 +1,7 @@
 FILE(GLOB examples_SRCS "*.cpp")
 
+ADD_CUSTOM_TARGET(all_examples)
+
 FOREACH(example_src ${examples_SRCS})
 GET_FILENAME_COMPONENT(example ${example_src} NAME_WE)
 ADD_EXECUTABLE(${example} ${example_src})
@@ -11,4 +13,5 @@ ADD_CUSTOM_COMMAND(
   COMMAND ${example_executable}
   ARGS >${CMAKE_CURRENT_BINARY_DIR}/${example}.out
 )
+ADD_DEPENDENCIES(all_examples ${example})
 ENDFOREACH(example_src)