turned off excessive graph generation in doxygen. (only ~500 graphs now)

doc/Doxyfile.in

@@ -2172,7 +2172,7 @@ INCLUDED_BY_GRAPH      = YES
 # The default value is: NO.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-CALL_GRAPH             = YES
+CALL_GRAPH             = NO
 
 # If the CALLER_GRAPH tag is set to YES then doxygen will generate a caller
 # dependency graph for every global function or class method.