wavcodec: fix WAV file loading

Read samples from “first sample byte” to “first sample byte + size”
instead of reading from “first sample byte” to “first header byte + size”.

It means we now:

- don't wrongfully truncate the end of the file from the size of the header,
- can load files with less samples than the header size.

Author: illwieckz

src/engine/audio/WavCodec.cpp

@@ -114,7 +114,8 @@ AudioData LoadWavCodec(std::string filename)
 	}
 
 	AudioData out { sampleRate, byteDepth, numChannels };
-	out.rawSamples.assign( audioFile.data() + dataOffset + 8, audioFile.data() + size );
+	auto firstSample = audioFile.data() + dataOffset + 8;
+	out.rawSamples.assign( firstSample, firstSample + size );
 
 	return out;
 }