Bugfix, if path was given the filename was not used at all.

src/audio/sfx_manager.cpp

@@ -593,7 +593,7 @@ SFXBuffer* SFXManager::loadSingleSfx(const XMLNode* node,
     // to load terrain specific sfx.
     const std::string full_path = (path == "")
                                 ? file_manager->getAsset(FileManager::SFX,filename)
-                                : path;
+                                : path+"/"+filename;
 
     SFXBuffer tmpbuffer(full_path, node);