Cool graphs in documentation.

doc/doxygen.cfg

@@ -789,7 +789,7 @@ CLASS_DIAGRAMS         = YES
 # toolkit from AT&T and Lucent Bell Labs. The other options in this section 
 # have no effect if this option is set to NO (the default)
 
-HAVE_DOT               = NO
+HAVE_DOT               = YES
 
 # If the CLASS_GRAPH and HAVE_DOT tags are set to YES then doxygen 
 # will generate a graph for each documented class showing the direct and 
@@ -839,7 +839,7 @@ GRAPHICAL_HIERARCHY    = YES
 # generated by dot. Possible values are gif, jpg, and png
 # If left blank gif will be used.
 
-DOT_IMAGE_FORMAT       = gif
+DOT_IMAGE_FORMAT       = png
 
 # The tag DOT_PATH can be used to specify the path where the dot tool can be 
 # found. If left blank, it is assumed the dot tool can be found on the path.