--split option is now available in aria2.changeOption.

--split option is now available in aria2.changeOption if a download is
waiting/paused in queue.

src/OptionHandlerFactory.cc

@@ -946,6 +946,7 @@ OptionHandlerFactory::createOptionHandlers()
     op->addTag(TAG_HTTP);
     op->setInitialOption(true);
     op->setChangeGlobalOption(true);
+    op->setChangeOptionForReserved(true);
     handlers.push_back(op);
   }
   {

src/RpcMethodImpl.cc

@@ -1134,6 +1134,9 @@ void changeOption
     sgl.normalize();
     dctx->setFileFilter(sgl);
   }
+  if(option.defined(PREF_SPLIT)) {
+    group->setNumConcurrentCommand(option.getAsInt(PREF_SPLIT));
+  }
   if(option.defined(PREF_MAX_DOWNLOAD_LIMIT)) {
     group->setMaxDownloadSpeedLimit
       (option.getAsInt(PREF_MAX_DOWNLOAD_LIMIT));