update doxygen target to use the Homebrew path /usr/local/bin

Little Go.xcodeproj/project.pbxproj

@@ -2058,7 +2058,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "# change directory because Doxyfile is configured with a relative input path \"..\"\ncd doxygen\n\n# clean the directory\nrm -rf html\n\n# generate docs\n/opt/local/bin/doxygen Doxyfile\n\n# open the html documentation\nopen html/index.html\n";
+			shellScript = "# change directory because Doxyfile is configured with a relative input path \"..\"\ncd doxygen\n\n# clean the directory\nrm -rf html\n\n# generate docs\n/usr/local/bin/doxygen Doxyfile\n\n# open the html documentation\nopen html/index.html\n";
 		};
 /* End PBXShellScriptBuildPhase section */
 

doc/README.developer

@@ -140,10 +140,10 @@ There is a "doxygen" target that can be used to transform the source code
 documentation into a set of HTML files. The target uses a shell script that
 assumes that Doxygen is installed in
 
-  /opt/local/bin
+  /usr/local/bin
 
-This is the standard path for the MacPorts project. If you have doxygen
-installed somewhere else (e.g. /sw/bin, /usr/local/bin) you need to change the
+This is the standard path for the Homebrew project. If you have doxygen
+installed somewhere else (e.g. /sw/bin, /opt/local/bin) you need to change the
 target's shell script.
 
 The Doxygen configuration file is located in
@@ -157,6 +157,6 @@ Notes about the configuration:
   are not included in the documentation process. Change this by setting
   EXTRACT_LOCAL_METHODS = YES inside Doxyfile.
 - Doxyfile is configured to look for the command line tool "dot" in
-    /opt/local/bin
+    /usr/local/bin
   dot is part of the Graphviz package and is used to generate a couple of
   diagram types (e.g. class diagrams, collaboration diagrams).

doxygen/Doxyfile

@@ -1352,7 +1352,7 @@ 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               = /opt/local/bin
+DOT_PATH               = /usr/local/bin
 
 # 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