Update to Qt 5.12.0.

Project files with MacOS clang RPATH to use proper paths for shared objects.
Minor path updates in favor of loading plugin libs.
Deployment script packaging using Qt way(macdeployqt).

sdrbase/plugin/pluginmanager.cpp

@@ -63,6 +63,10 @@ void PluginManager::loadPluginsPart(const QString& pluginsSubDir)
 {
     QString applicationDirPath = QCoreApplication::instance()->applicationDirPath();
     QString applicationLibPath = applicationDirPath + "/../lib/" + pluginsSubDir;
+#ifdef __APPLE__
+    applicationLibPath.clear();
+    applicationLibPath.append(applicationDirPath + "/../Frameworks/" + pluginsSubDir);
+#endif
     QString applicationBuildPath = applicationDirPath + "/" + pluginsSubDir;
     qDebug() << "PluginManager::loadPlugins: " << qPrintable(applicationLibPath) << "," << qPrintable(applicationBuildPath);