Changed the playing code to use Playlists managed by a PlaylistManager. This allows you to have randomized playlists and stuff. Also, you can now access special functions via the contents of RFID tags. See the README for a list of available modes.

include/playlist.h

@@ -0,0 +1,25 @@
+#pragma once
+#include <Arduino.h>
+#include <vector>
+
+class Playlist {
+private:
+	uint32_t _position = 0;
+	uint32_t _current_track = 0;
+	bool _shuffled = false;
+	std::vector<String> _files;
+public:
+	Playlist(String path);
+	bool has_track_next();
+	bool has_track_prev();
+	bool track_next();
+	bool track_prev();
+	void track_restart();
+	void reset();
+	bool is_empty();
+	String get_current_file();
+	uint32_t get_position();
+	void set_position(uint32_t p);
+	void shuffle(uint8_t random_offset=0);
+	bool is_fresh();
+};