Change #6685: Replace Win32 music driver with one not depending on MCI

MCI MIDI is poorly supported on newer versions of Windows and can cause large
delays at the beginning of tracks.

The new driver is based on a from-scratch reader for Standard MIDI Files. This
should be re-usable in other music drivers too, and can allow for finer control
of playback in general.

It also provides a better framework for reading MIDI data from other formats
than just SMF.

src/music/midifile.hpp

@@ -0,0 +1,44 @@
+/* $Id$ */
+
+/*
+* This file is part of OpenTTD.
+* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* @file midifile.hpp Parser for standard MIDI files */
+
+#ifndef MUSIC_MIDIFILE_HPP
+#define MUSIC_MIDIFILE_HPP
+
+#include "../stdafx.h"
+#include "../core/smallvec_type.hpp"
+#include "midi.h"
+#include <vector>
+
+struct MidiFile {
+	struct DataBlock {
+		uint32 ticktime;           ///< tick number since start of file this block should be triggered at
+		uint32 realtime;           ///< real-time (microseconds) since start of file this block should be triggered at
+		SmallVector<byte, 8> data; ///< raw midi data contained in block
+		DataBlock(uint32 _ticktime = 0) : ticktime(_ticktime) { }
+	};
+	struct TempoChange {
+		uint32 ticktime; ///< tick number since start of file this tempo change occurs at
+		uint32 tempo;    ///< new tempo in microseconds per tick
+		TempoChange(uint32 _ticktime, uint32 _tempo) : ticktime(_ticktime), tempo(_tempo) { }
+	};
+
+	std::vector<DataBlock> blocks;   ///< sequential time-annotated data of file, merged to a single track
+	std::vector<TempoChange> tempos; ///< list of tempo changes in file
+	uint16 tickdiv;                  ///< ticks per quarter note
+
+	bool LoadFile(const char *filename);
+	void MoveFrom(MidiFile &other);
+
+	static bool ReadSMFHeader(const char *filename, SMFHeader &header);
+	static bool ReadSMFHeader(FILE *file, SMFHeader &header);
+};
+
+#endif /* MUSIC_MIDIFILE_HPP */