require openslide 3.2.5 or greater

3.2.4 and earlier have a horrible performance problem

ChangeLog

@@ -7,8 +7,8 @@
 - better im_shrink()
 - added vips_sequential()
 - new vips_sink_memory() keeps read ordering
-- tiff reader supports sequential read
-- jpeg reader supports sequential read
+- tiff, jpeg, png readers support sequential read
+- max/min avoid NaN
 
 20/8/11 started 7.27.0
 - version bump for new dev cycle

TODO

@@ -1,12 +1,6 @@
 blocking bugs
 =============
 
-- argh
-
-	(nip2:11576): GLib-GObject-WARNING **: value "-0.000000" of type 
-	`gdouble' is invalid or out of range for property `yres' of 
-	type `gdouble'
-
 - new binding is still missing constants 
 
   how do boxed types work? confusing

configure.in

@@ -481,11 +481,11 @@ AC_ARG_WITH([openslide],
   AS_HELP_STRING([--without-openslide], [build without OpenSlide (default: test)]))
 
 if test x"$with_openslide" != x"no"; then
-  PKG_CHECK_MODULES(OPENSLIDE, openslide >= 3.2.0,
-    [AC_DEFINE(HAVE_OPENSLIDE,1,[define if you have OpenSlide >= 3.2.0 installed.])
+  PKG_CHECK_MODULES(OPENSLIDE, openslide >= 3.2.5,
+    [AC_DEFINE(HAVE_OPENSLIDE,1,[define if you have OpenSlide >= 3.2.5 installed.])
      with_openslide=yes
      PACKAGES_USED="$PACKAGES_USED openslide"],
-    [AC_MSG_WARN([OpenSlide >= 3.2.0 not found; disabling virtual slide support])
+    [AC_MSG_WARN([OpenSlide >= 3.2.5 not found; disabling virtual slide support])
      with_openslide=no
     ])
 fi
@@ -737,7 +737,7 @@ accelerate loops with orc: 		$with_orc
 ICC profile support with lcms: 		$with_lcms (version $with_lcms_ver)
 file import with OpenEXR: 		$with_OpenEXR
 file import with OpenSlide:		$with_openslide
-  (requires openslide-3.2.0 or later)
+  (requires openslide-3.2.5 or later)
 file import with matio: 		$with_matio
 file import with cfitsio: 		$with_cfitsio
 text rendering with pangoft2: 		$with_pangoft2