Separate includes into sections and alphabetize them

Okay, so basically here's the include layout that this game now
consistently uses:

[The "main" header file, if any (e.g. Graphics.h for Graphics.cpp)]
[blank line]
[All system includes, such as tinyxml2/physfs/utfcpp/SDL]
[blank line]
[All project includes, such as Game.h/Entity.h/etc.]

And if applicable, another blank line, and then some special-case
include screwy stuff (take a look at editor.cpp or FileSystemUtils.cpp,
for example, they have ifdefs and defines with their includes).

desktop_version/src/Music.h

@@ -1,11 +1,11 @@
 #ifndef MUSIC_H
 #define MUSIC_H
 
-#include "SoundSystem.h"
-#include "BinaryBlob.h"
-
 #include <vector>
 
+#include "BinaryBlob.h"
+#include "SoundSystem.h"
+
 #define musicroom(rx, ry) ((rx) + ((ry) * 20))
 
 class musicclass