ENGINES: Change behaviour of EngineMan::getPlugins.

- Changed so we can get any type of plugins.
- This used to always return PLUGIN_TYPE_ENGINE.
- Because now we can differentiate between engines and metaengine, this must be changed.
- For now, return METAENGINE by default

base/plugins.cpp

@@ -652,8 +652,8 @@ DetectionResults EngineManager::detectGames(const Common::FSList &fslist) const
 	return DetectionResults(candidates);
 }
 
-const PluginList &EngineManager::getPlugins() const {
-	return PluginManager::instance().getPlugins(PLUGIN_TYPE_ENGINE);
+const PluginList &EngineManager::getPlugins(const PluginType fetchPluginType) const {
+	return PluginManager::instance().getPlugins(fetchPluginType);
 }
 
 namespace {