Change CMakeLists.txt to add 2d_game project, and added irrKlang to LIBS.

Added irrKlang.dll and ikpMP2.dll to dlls folder.  Added irrKlang as a
sub-folder under includes.  Added irrKlang.lib to lib folder.  At this point
running cmake gave an error it couldn't find source files under 2d_game.
Moved 2d_game source up one folder level, then cmake found the files.

includes/irrKlang/ik_IAudioRecorder.h

@@ -0,0 +1,110 @@
+// Copyright (C) 2002-2018 Nikolaus Gebhardt
+// This file is part of the "irrKlang" library.
+// For conditions of distribution and use, see copyright notice in irrKlang.h
+
+#ifndef __I_IRRKLANG_AUDIO_RECORDER_H_INCLUDED__
+#define __I_IRRKLANG_AUDIO_RECORDER_H_INCLUDED__
+
+#include "ik_IRefCounted.h"
+#include "ik_ISoundSource.h"
+
+
+namespace irrklang
+{
+	class ICapturedAudioDataReceiver;
+
+	//! Interface to an audio recorder. Create it using the createIrrKlangAudioRecorder() function.
+	/** It creates sound sources into an ISoundEngine which then can be played there. 
+	See @ref recordingAudio for an example on how to use this. */
+	class IAudioRecorder : public virtual IRefCounted
+	{
+	public:
+
+		//! Starts recording audio. 
+		/** Clears all possibly previously recorded buffered audio data and starts to record. 
+		When finished recording audio data, call stopRecordingAudio(). 
+		All recorded audio data gets stored into an internal audio buffer, which
+		can then be accessed for example using addSoundSourceFromRecordedAudio() or
+		getRecordedAudioData(). For recording audio data not into an internal audio
+		buffer, use startRecordingCustomHandledAudio().
+		\param sampleRate: Sample rate of the recorded audio.
+		\param sampleFormat: Sample format of the recorded audio.
+		\param channelCount: Amount of audio channels.
+		\return Returns true if successfully started recording and false if not.*/
+		virtual bool startRecordingBufferedAudio(ik_s32 sampleRate=22000, 
+		                                         ESampleFormat sampleFormat=ESF_S16,
+												 ik_s32 channelCount=1) = 0;
+
+		//! Starts recording audio. 
+		/** Clears all possibly previously recorded buffered audio data and starts to record 
+		audio data, which is delivered to a custom user callback interface. 
+		When finished recording audio data, call stopRecordingAudio(). If instead of 
+		recording the data to the receiver interface recording into a managed buffer
+		is wished, use startRecordingBufferedAudio() instead.
+		\param receiver: Interface to be implemented by the user, gets called once for each
+		captured audio data chunk. 
+		\param sampleRate: Sample rate of the recorded audio.
+		\param sampleFormat: Sample format of the recorded audio.
+		\param channelCount: Amount of audio channels.
+		\return Returns true if successfully started recording and false if not. */
+		virtual bool startRecordingCustomHandledAudio(ICapturedAudioDataReceiver* receiver,
+			                                          ik_s32 sampleRate=22000,
+													  ESampleFormat sampleFormat=ESF_S16,
+													  ik_s32 channelCount=1) = 0;
+
+		//! Stops recording audio.
+		virtual void stopRecordingAudio() = 0;
+
+		//! Creates a sound source for the recorded audio data.
+		/** The returned sound source pointer then can be used to play back the recorded audio data
+		using ISoundEngine::play2D(). This method only will succeed if the audio was recorded using
+		startRecordingBufferedAudio() and audio recording is currently stopped.
+		\param soundName Name of the virtual sound file (e.g. "someRecordedAudio"). You can also use this
+		name when calling play3D() or play2D().  */
+		virtual ISoundSource* addSoundSourceFromRecordedAudio(const char* soundName) = 0;
+
+		//! Clears recorded audio data buffer, freeing memory.
+		/** This method will only succeed if audio recording is currently stopped. */
+		virtual void clearRecordedAudioDataBuffer() = 0;
+
+		//! Returns if the recorder is currently recording audio.
+		virtual bool isRecording() = 0;
+
+		//! Returns the audio format of the recorded audio data. 
+		/** Also contains informations about the length of the recorded audio stream. */
+		virtual SAudioStreamFormat getAudioFormat() = 0;
+
+		//! Returns a pointer to the recorded audio data.
+		/** This method will only succeed if audio recording is currently stopped and
+		something was recorded previously using startRecordingBufferedAudio(). 
+		The lenght of the buffer can be retrieved using 
+		getAudioFormat().getSampleDataSize(). Note that the pointer is only valid
+		as long as not clearRecordedAudioDataBuffer() is called or another sample is
+		recorded.*/
+		virtual void* getRecordedAudioData() = 0;
+
+		//! returns the name of the sound driver, like 'ALSA' for the alsa device.
+		/** Possible returned strings are "NULL", "ALSA", "CoreAudio", "winMM", 
+		"DirectSound" and "DirectSound8". */
+		virtual const char* getDriverName() = 0;
+	};
+
+
+	//! Interface to be implemented by the user if access to the recorded audio data is needed.
+	/** Is used as parameter in IAudioRecorder::startRecordingCustomHandledAudio. */
+	class ICapturedAudioDataReceiver : public IRefCounted
+	{
+	public:
+
+		//! Gets called once for each captured audio data chunk.
+		/** See IAudioRecorder::startRecordingCustomHandledAudio for details.
+		\param audioData: Pointer to a part of the recorded audio data
+		\param lengthInBytes: Amount of bytes in the audioData buffer.*/
+		virtual void OnReceiveAudioDataStreamChunk(unsigned char* audioData, unsigned long lengthInBytes) = 0;
+	};
+
+
+} // end namespace irrklang
+
+
+#endif