Consistently use angle brackets for SDL.h includes

That's how it should be done, because the SDL headers aren't going to be
installed in this repository. The game was a bit inconsistent before but
now it isn't anymore.

desktop_version/src/BlockV.h

@@ -1,7 +1,7 @@
 #ifndef BLOCKV_H
 #define BLOCKV_H
 
-#include "SDL.h"
+#include <SDL.h>
 #include <string>
 
 class blockclass

desktop_version/src/Game.h

@@ -3,7 +3,7 @@
 
 #include <vector>
 #include <string>
-#include "SDL.h"
+#include <SDL.h>
 #include "Maths.h"
 #include "UtilityClass.h"
 #include "GraphicsUtil.h"

desktop_version/src/GraphicsResources.h

@@ -1,7 +1,7 @@
 #ifndef GRAPHICSRESOURCES_H
 #define GRAPHICSRESOURCES_H
 
-#include "SDL.h"
+#include <SDL.h>
 
 class GraphicsResources
 {

desktop_version/src/GraphicsUtil.h

@@ -1,7 +1,7 @@
 #ifndef GRAPHICSUTIL_H
 #define GRAPHICSUTIL_H
 
-#include "SDL.h"
+#include <SDL.h>
 
 struct colourTransform
 {

desktop_version/src/KeyPoll.h

@@ -5,7 +5,7 @@
 #include <vector>
 #include <map> // FIXME: I should feel very bad for using C++ -flibit
 
-#include "SDL.h"
+#include <SDL.h>
 
 #include "Screen.h"
 

desktop_version/src/Textbox.h

@@ -1,7 +1,7 @@
 #ifndef TEXTBOX_H
 #define TEXTBOX_H
 
-#include "SDL.h"
+#include <SDL.h>
 #include <string>
 #include <vector>
 

desktop_version/src/UtilityClass.cpp

@@ -1,6 +1,6 @@
 #include "UtilityClass.h"
 
-#include "SDL.h"
+#include <SDL.h>
 
 #include <cctype>
 #include <sstream>