add doxygen support

Since we have no doxygen compatible code comments (we hardly have
comments at all ;) there is not much documentation to be extracted. But
this is still useful, as doxy generates us nice callgraphs showing the
internal code flow chaos. :)

Usage is as follows: after having run ./autogen.sh, doxygen can be
triggered by simply issuing 'make doxy'. This will generate a doxy
config if none exists, and preset some stuff inside (especially
parsing of undocumented stuff). Before all consecutive invocations, the
doxy config (named 'Doxyfile') can be customised to one's personal
needs.

.gitignore

@@ -1,6 +1,7 @@
 *.orig
 *~
 .*.swp
+Doxyfile
 Makefile
 Makefile.in
 aclocal.m4

Makefile.am

@@ -48,4 +48,24 @@ ACLOCAL_AMFLAGS = -I m4
 distclean-local:
 	/bin/rm -rf *.cache *~
 
+Doxyfile:
+	doxygen -g
+	sed -e 's/^\(PROJECT_NAME *=\).*$$/\1 conky/' \
+	    -e 's/^\(PROJECT_NUMBER *=\).*$$/\1 1.6/' \
+	    -e 's/^\(OPTIMIZE_OUTPUT_FOR_C *=\).*$$/\1 YES/' \
+	    -e 's/^\(EXTRACT_ALL *=\).*$$/\1 YES/' \
+	    -e 's/^\(EXTRACT_PRIVATE *=\).*$$/\1 YES/' \
+	    -e 's/^\(EXTRACT_STATIC *=\).*$$/\1 YES/' \
+	    -e 's/^\(INPUT *=\).*$$/\1 "src"/' \
+	    -e 's/^\(SOURCE_BROWSER *=\).*$$/\1 YES/' \
+	    -e 's/^\(MACRO_EXPANSION *=\).*$$/\1 YES/' \
+	    -e 's/^\(HAVE_DOT *=\).*$$/\1 YES/' \
+	    -e 's/^\(CALL_GRAPH *=\).*$$/\1 YES/' \
+	    -e 's/^\(CALLER_GRAPH *=\).*$$/\1 YES/' -i Doxyfile
+
+doxy: Doxyfile
+	doxygen $<
+
+.PHONY: distclean-local doxy
+
 # vi:set ts=8 sw=8 noet ai nocindent syntax=automake: