Bump version to 0.2.18

Author: Prior99

package.json

@@ -9,7 +9,7 @@
     "pngjs",
     "node-libpng"
   ],
-  "version": "0.2.17",
+  "version": "0.2.18",
   "description": "Unofficial bindings for node to libpng.",
   "main": "dist/index.js",
   "author": "Frederick Gnodtke",