Update NEWS and prepare for 4.13.4 release.

NEWS

+4.13.4
+======
+- Fix segfault in xfconf_cache_set_property_reply_handler when 
+  multiple calls are made (bug #13825)
+- Allow to store empty arrays (bug #13791)
+- Fix a path in xfconf_cache_set where the mutex isn't locked (bug #13790)
+
 4.13.3
 ======
 - Flush gdbus connection on xfconf_shutdown

configure.ac.in

@@ -10,10 +10,10 @@ m4_define([libxfconf_verinfo], [3:0:0])
 m4_define([libxfconf_version_api], [0])
 m4_define([xfconf_version_major], [4])
 m4_define([xfconf_version_minor], [13])
-m4_define([xfconf_version_micro], [3])
+m4_define([xfconf_version_micro], [4])
 m4_define([xfconf_version_nano], [])
-m4_define([xfconf_version_build], [@REVISION@])
-m4_define([xfconf_version_tag], [git])
+m4_define([xfconf_version_build], [])
+m4_define([xfconf_version_tag], [])
 m4_define([xfconf_version], [xfconf_version_major().xfconf_version_minor().xfconf_version_micro()ifelse(xfconf_version_nano(), [], [], [.xfconf_version_nano()])ifelse(xfconf_version_tag(), [git], [xfconf_version_tag()-xfconf_version_build()], [xfconf_version_tag()])])
 
 m4_define([xfconf_default_debug], [ifelse(xfconf_version_tag(), [git], [yes], [minimum])])