Resolve "Shader Program Class"

Closes #10 (closed)

config/ext/Doxygen.cmake

+
+# check if Doxygen is installed
+find_package(Doxygen)
+
+if (DOXYGEN_FOUND)
+	# note the option ALL which allows to build the docs together with the application
+	add_custom_target( doc_doxygen ALL
+			COMMAND ${DOXYGEN_EXECUTABLE} ${PROJECT_SOURCE_DIR}/Doxyfile
+			WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+			COMMENT "Generating API documentation with Doxygen"
+			VERBATIM )
+else (DOXYGEN_FOUND)
+	message(WARNING "Doxygen need to be installed to generate the doxygen documentation")
+endif (DOXYGEN_FOUND)