Replicate EVALSHA as EVAL taking a dictionary of sha1 -> script source code.

src/object.c

@@ -192,6 +192,23 @@ void decrRefCount(void *obj) {
     }
 }
 
+/* This function set the ref count to zero without freeing the object.
+ * It is useful in order to pass a new object to functions incrementing
+ * the ref count of the received object. Example:
+ *
+ *    functionThatWillIncrementRefCount(resetRefCount(CreateObject(...)));
+ *
+ * Otherwise you need to resort to the less elegant pattern:
+ *
+ *    *obj = createObject(...);
+ *    functionThatWillIncrementRefCount(obj);
+ *    decrRefCount(obj);
+ */
+robj *resetRefCount(robj *obj) {
+    obj->refcount = 0;
+    return obj;
+}
+
 int checkType(redisClient *c, robj *o, int type) {
     if (o->type != type) {
         addReply(c,shared.wrongtypeerr);