BUG: Add QUIET option to FIND_PACKAGE( Doxygen ) in Documentation/CMakeLists.txt

That will avoid to print the unwanted message:
Could NOT find Doxygen  (missing:  DOXYGEN_EXECUTABLE)

The following custom message should be displayed instead:

"Warning: Dot not found - Documentation will not be created"

Documentation/CMakeLists.txt

@@ -1,4 +1,4 @@
-FIND_PACKAGE( Doxygen )
+FIND_PACKAGE( Doxygen QUIET)
 
 IF( DOXYGEN_FOUND )
   IF( DOXYGEN_DOT_FOUND )