Disabled caller graphs as they are only of internal interest.

doc/doxy.config.in

@@ -1356,7 +1356,7 @@ CALL_GRAPH             = NO
 # the time of a run. So in most cases it will be better to enable caller 
 # graphs for selected functions only using the \callergraph command.
 
-CALLER_GRAPH           = YES
+CALLER_GRAPH           = NO
 
 # If the GRAPHICAL_HIERARCHY and HAVE_DOT tags are set to YES then doxygen 
 # will graphical hierarchy of all classes instead of a textual one.