Print attributes for ppm

src/imgio.c

@@ -233,3 +233,11 @@ inherit_from_ppm(const PPM* in)
 	};
 	return image;
 }
+
+/** The Second image gets merged into the first.
+ * The First image obtains attributes from the second image that were not found.
+*/
+PPM
+merge_ppm(const PPM* in_1, const PPM* in_2) {
+        if(in) 
+}