fixes jitters by using signals/slots to pass image buffers around

Updating values rapidly would cause strange jitters as a
byproduct of the viewer trying to update from the renderer while
it was still working. Rather than the viewer trying to access the
the renderer, we now send textures in the initial update signal
to keep everything synchronized.

app/window/mainwindow/mainwindow.cpp

@@ -152,7 +152,7 @@ void olive::MainWindow::closeEvent(QCloseEvent *e)
   // FIXME: Test code - We have no cache management and the cache is very much testing only, so we delete it on close
   //                    as to not clog up HDD space
   QDir(GetMediaCacheLocation()).removeRecursively();
-  QDir(GetMediaIndexLocation()).removeRecursively();
+  //QDir(GetMediaIndexLocation()).removeRecursively();
   // End test code
 
   QMainWindow::closeEvent(e);