Removed trailing spaces in the most relevant files

Command used for the job:
egrep -rl ' $' --include *.c --include *.h --include  *.s --include  *.inc --include  *.txt *  | xargs sed -i 's/\s\+$//g'

Credits to Grant Murphy from Stack Overflow.

src/intro_credits_graphics.c

@@ -13,7 +13,7 @@
     and the credit sequence, where the player bikes along a grassy path.
 
     These graphics are placed in graphics/intro/scene_2 to keep
-    all of the intro graphics files together, though it includes 
+    all of the intro graphics files together, though it includes
     the related graphics that are used only by the credits.
 */
 
@@ -1039,7 +1039,7 @@ static void SpriteCB_MovingScenery(struct Sprite *sprite)
 {
     s32 x;
     s16 state = gIntroCredits_MovingSceneryState;
-    
+
     if (state != INTROCRED_SCENERY_FROZEN)
     {
         switch (state)