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/Input.cpp

@@ -1,21 +1,18 @@
-#include "Logic.h"
-#include "Script.h"
-#include "Credits.h"
-
-#include "MakeAndPlay.h"
-
 #include <tinyxml2.h>
 
-#include "FileSystemUtils.h"
-
+#include "Credits.h"
 #include "editor.h"
 #include "Entity.h"
 #include "Enums.h"
+#include "FileSystemUtils.h"
 #include "Game.h"
 #include "Graphics.h"
 #include "KeyPoll.h"
+#include "Logic.h"
+#include "MakeAndPlay.h"
 #include "Map.h"
 #include "Music.h"
+#include "Script.h"
 
 void updatebuttonmappings(int bind)
 {