Implement backtraces on Windows.

Much !!FUN!! was had

gui/MainWindow.cpp

@@ -782,6 +782,11 @@ void MainWindow::setCatBackground(bool enabled)
 
 void MainWindow::on_actionAddInstance_triggered()
 {
+#ifdef TEST_SEGV
+	// For further testing stuff.
+	int v = *((int*)-1);
+#endif
+	
 	if (!MMC->minecraftlist()->isLoaded() && m_versionLoadTask &&
 		m_versionLoadTask->isRunning())
 	{