New API to force propagation.

The old REDIS_CMD_FORCE_REPLICATION flag was removed from the
implementation of Redis, now there is a new API to force specific
executions of a command to be propagated to AOF / Replication link:

    void forceCommandPropagation(int flags);

The new API is also compatible with Lua scripting, so a script that will
execute commands that are forced to be propagated, will also be
propagated itself accordingly even if no change to data is operated.

As a side effect, this new design fixes the issue with scripts not able
to propagate PUBLISH to slaves (issue #873).

src/scripting.c

@@ -1042,6 +1042,7 @@ void scriptCommand(redisClient *c) {
         }
         addReplyBulkCBuffer(c,funcname+2,40);
         sdsfree(sha);
+        forceCommandPropagation(c,REDIS_PROPAGATE_REPL);
     } else if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"kill")) {
         if (server.lua_caller == NULL) {
             addReplySds(c,sdsnew("-NOTBUSY No scripts in execution right now.\r\n"));