* Doxygen: generate collaboration diagrams if dot is available

configure.ac

@@ -125,10 +125,18 @@ if test "${enable_doc}" != "no"; then
         AC_MSG_RESULT(no)
       fi
     fi
+    AC_PATH_PROG(DOT, dot, no)
+    if test "${DOT}" != "no"; then
+      AC_MSG_RESULT(yes)
+      USE_DOT="YES"
+    else
+      USE_DOT="NO"
+    fi
   fi
 fi
 AM_CONDITIONAL(BUILD_DOCUMENTATION, test "${DOXYGEN}" != "no")
 AM_CONDITIONAL(USE_LATEX, test "${LATEX}" != "no")
+AM_CONDITIONAL(USE_DOT, test "${DOT}" != "no")
 
 dnl No exceptions
 CXXFLAGS="${CXXFLAGS} -fno-exceptions -fno-rtti"
@@ -411,6 +419,7 @@ LOL_LIBS="$LOL_LIBS $SDL_LIBS $GL_LIBS $EGL_LIBS $LIBPNG_LIBS $D3D_LIBS"
 AC_SUBST(LOL_CFLAGS)
 AC_SUBST(LOL_LIBS)
 
+AC_SUBST(USE_DOT)
 
 AC_CONFIG_FILES(
  [Makefile

doc/doxygen.cfg.in

@@ -1359,14 +1359,14 @@ MSCGEN_PATH            =
 # inheritance and usage relations if the target is undocumented
 # or is not a class.
 
-HIDE_UNDOC_RELATIONS   = YES
+HIDE_UNDOC_RELATIONS   = NO
 
 # If you set the HAVE_DOT tag to YES then doxygen will assume the dot tool is
 # available from the path. This tool is part of Graphviz, a graph visualization
 # 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               = @USE_DOT@
 
 # By default doxygen will write a font called FreeSans.ttf to the output
 # directory and reference it in all dot files that doxygen generates. This
@@ -1472,7 +1472,7 @@ 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 in the path.
 
-DOT_PATH               =
+DOT_PATH               = @DOT@
 
 # The DOTFILE_DIRS tag can be used to specify one or more directories that
 # contain dot files that are included in the documentation (see the