Add upgrade patches for 1.6 RC1-RC4. Upgrade to RC5 is staged as 1.6 RC1-4

include/upgrader/patches/15af7cd3-98ae1ed2.patch.sql

+/*
+ * @version=1.6RC1-4
+ * 
+ * Stage RC2 for 1.6RC5 upgrade
+ */
+
+UPDATE `%TABLE_PREFIX%config`
+    SET `ostversion`='1.6 RC1-4';

include/upgrader/patches/2e20a0eb-98ae1ed2.patch.sql

+/*
+ * @version=1.6RC1-4
+ * 
+ * Stage RC4 for 1.6RC5 upgrade
+ */
+
+UPDATE `%TABLE_PREFIX%config`
+    SET `ostversion`='1.6 RC1-4';

include/upgrader/patches/a67ba35e-98ae1ed2.patch.sql

+/*
+ * @version=1.6RC1-4
+ * 
+ * Stage RC3 for 1.6RC5 upgrade
+ */
+
+UPDATE `%TABLE_PREFIX%config`
+    SET `ostversion`='1.6 RC1-4';

include/upgrader/patches/aee589ab-98ae1ed2.patch.sql

+/*
+ * @version=1.6RC1-4
+ * 
+ * Stage RC1 for 1.6RC5 upgrade
+ */
+
+UPDATE `%TABLE_PREFIX%config`
+    SET `ostversion`='1.6 RC1-4';