Geo: GEOADD implementation improved, replication fixed

1. We no longer use a fake client but just rewriting.
2. We group all the inserts into a single ZADD dispatch (big speed win).
3. As a side effect of the correct implementation, replication works.
4. The return value of the command is now correct.

src/networking.c

@@ -1527,6 +1527,16 @@ void rewriteClientCommandVector(redisClient *c, int argc, ...) {
     va_end(ap);
 }
 
+/* Completely replace the client command vector with the provided one. */
+void replaceClientCommandVector(redisClient *c, int argc, robj **argv) {
+    freeClientArgv(c);
+    zfree(c->argv);
+    c->argv = argv;
+    c->argc = argc;
+    c->cmd = lookupCommandOrOriginal(c->argv[0]->ptr);
+    redisAssertWithInfo(c,NULL,c->cmd != NULL);
+}
+
 /* Rewrite a single item in the command vector.
  * The new val ref count is incremented, and the old decremented. */
 void rewriteClientCommandArgument(redisClient *c, int i, robj *newval) {