Untabify every single file

YOLO.

This is a repeat of #642. As before, I just did

    rg -l '\t' | xargs -n 1 sed -i -e 's/\t/    /g'

inside the desktop_version/ folder.

desktop_version/src/SoundSystem.h

@@ -6,23 +6,23 @@
 class MusicTrack
 {
 public:
-	MusicTrack(const char* fileName);
-	MusicTrack(SDL_RWops *rw);
-	Mix_Music *m_music;
-	bool m_isValid;
+    MusicTrack(const char* fileName);
+    MusicTrack(SDL_RWops *rw);
+    Mix_Music *m_music;
+    bool m_isValid;
 };
 
 class SoundTrack
 {
 public:
-	SoundTrack(const char* fileName);
-	Mix_Chunk *sound;
+    SoundTrack(const char* fileName);
+    Mix_Chunk *sound;
 };
 
 class SoundSystem
 {
 public:
-	SoundSystem(void);
+    SoundSystem(void);
 };
 
 #endif /* SOUNDSYSTEM_H */