* builds/freetype.mk (DOC_DIR): New variable.
(refdoc): Use *_DIR variables.
(distclean): Remove documentation files.

* builds/detect.mk (std_setup, dos_setup): Mention `make refdoc'.

* configure: Set DOC_DIR variable.

* builds/freetype.mk (refdoc): New target to build the
documentation.
(.PHONY): Updated.

* include/freetype/freetype.h: Improve documentation of FT_CharMap.
* include/freetype/ftimage,h: Fix documentation of FT_OUTLINE_FLAGS.
* include/freetype/tttables.h: Document FT_Sfnt_Tag.
diff --git a/configure b/configure
index 1198380..c8a5657 100644
--- a/configure
+++ b/configure
@@ -46,11 +46,13 @@
 # build a dummy Makefile if we are not building in the source tree
 
 if test "$abs_curr_dir" != "$abs_ft2_dir"; then
-  echo "OBJ_DIR=$abs_curr_dir"          > Makefile
-  echo "TOP_DIR=$abs_ft2_dir"          >> Makefile
-  echo "OBJ_BUILD=$abs_curr_dir"       >> Makefile
-  echo "LIBTOOL=$abs_curr_dir/libtool" >> Makefile
-  echo "include $abs_ft2_dir/Makefile" >> Makefile
+  mkdir reference
+  echo "TOP_DIR=$abs_ft2_dir"             > Makefile
+  echo "OBJ_DIR=$abs_curr_dir"           >> Makefile
+  echo "OBJ_BUILD=$abs_curr_dir"         >> Makefile
+  echo "DOC_DIR=$abs_curr_dir/reference" >> Makefile
+  echo "LIBTOOL=$abs_curr_dir/libtool"   >> Makefile
+  echo "include $abs_ft2_dir/Makefile"   >> Makefile
 fi
 
 # call make