Move all fixed-timestep render updates to new file RenderFixed.cpp

As part of fixing #464, I'll need to move these pieces of code around
easily. In #220 I just kind of shoved them awkwardly in whatever
fixed function would be last called in the gamestate loop, which I
shouldn't have done as I've now had to make formal fixed-render
functions anyway. Because these fixed functions need to be called
directly before a render function, and I'm fixing the order to put
render functions in their proper place, so I need to be able to move
these around easily, and making them function calls instead of inlined
makes them easier to manipulate.

desktop_version/src/Input.cpp

@@ -8,10 +8,10 @@
 #include "Game.h"
 #include "Graphics.h"
 #include "KeyPoll.h"
-#include "Logic.h"
 #include "MakeAndPlay.h"
 #include "Map.h"
 #include "Music.h"
+#include "RenderFixed.h"
 #include "Script.h"
 #include "UtilityClass.h"