Bump version to 2.3.1.0
diff --git a/variables.h b/variables.h
index 5de6cd6..e6c28b7 100644
--- a/variables.h
+++ b/variables.h
@@ -17,7 +17,7 @@
 #ifndef _VARIABLES_HEADER_
 #define _VARIABLES_HEADER_
 
-#define TW_VERSION_STR              "2.3.0.4"
+#define TW_VERSION_STR              "2.3.1.0"
 
 #define TW_USE_COMPRESSION_VAR      "tw_use_compression"
 #define TW_IGNORE_IMAGE_SIZE        "tw_ignore_image_size"