[Portable] Save loaded plugins with relative path.

It is now possible to correctly load plugins even when
eg. disk label on Windows changes.

CHANGELOG

@@ -7,6 +7,7 @@ Version 1.5.0
     * cancel upload when trying to upload non-readable files
     * GreaseMonkey: added support for GM_Settings
     * fixed: size of preferences dialog on low-res screens
+    * fixed: loading plugins with relative paths in portable build
 
 Version 1.4.1
     * released 15 March 2013

src/lib/plugins/plugins.cpp

@@ -163,6 +163,10 @@ void Plugins::loadAvailablePlugins()
 
     QStringList dirs;
     dirs << mApp->DATADIR + "plugins/"
+         // Portable build: Load only plugins from DATADIR/plugins/ directory.
+         // Loaded plugins are saved with relative path, instead of absolute for
+         // normal build.
+#ifndef PORTABLE_BUILD
 #if defined(QZ_WS_X11) && !defined(NO_SYSTEM_DATAPATH)
 #ifdef USE_LIBPATH
          << USE_LIBPATH "qupzilla/"
@@ -171,6 +175,7 @@ void Plugins::loadAvailablePlugins()
 #endif
 #endif
          << mApp->PROFILEDIR + "plugins/";
+#endif
 
     foreach (const QString &dir, dirs) {
         QDir pluginsDir = QDir(dir);

src/lib/preferences/pluginsmanager.cpp

@@ -113,7 +113,11 @@ void PluginsManager::save()
         if (item->checkState() == Qt::Checked) {
             const Plugins::Plugin plugin = item->data(Qt::UserRole + 10).value<Plugins::Plugin>();
 
+#ifndef PORTABLE_BUILD
             allowedPlugins.append(plugin.fullPath);
+#else
+            allowedPlugins.append(mApp->DATADIR + "plugins/" + plugin.fileName);
+#endif
         }
     }