Don't read all dirs at startup.

src/playlist_manager.cpp

@@ -6,6 +6,7 @@ PlaylistManager::PlaylistManager() {
 	SPIMaster::enable_sd();
 	current_rfid_tag_id = String("");
 
+	/*
 	File root = SD.open("/");
 	while(File entry = root.openNextFile()) {
 		if (entry.isDirectory()) {
@@ -17,6 +18,8 @@ PlaylistManager::PlaylistManager() {
 			}
 		}
 	}
+	root.close();
+	*/
 
 	if (!SD.exists("/_mapping.txt")) {
 		Serial.println("WARNING: /_mapping.txt not found!");
@@ -37,7 +40,7 @@ PlaylistManager::PlaylistManager() {
 				Serial.printf("  Adding mapping: %s=>%s\n", rfid_id.c_str(), folder.c_str());
 				map[rfid_id] = folder;
 				
-				if (folder.charAt(0)=='/') {
+				/*if (folder.charAt(0)=='/') {
 					bool found=false;
 					for (String f: dirs) {
 						if (f.equals(folder)) {
@@ -48,12 +51,11 @@ PlaylistManager::PlaylistManager() {
 					if (!found) {
 						Serial.printf("WARNING: Found mapping for RFID id %s which maps to non-existing folder %s!\n", rfid_id.c_str(), folder.c_str());
 					}
-				}
+				}*/
 			}
 		}
 		f.close();
 	}
-	root.close();
 }
 
 Playlist PlaylistManager::get_playlist(String rfid_id) {