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/battle_ai_switch_items.c

@@ -866,7 +866,7 @@ static bool8 ShouldUseItem(void)
                 *(gBattleStruct->AI_itemFlags + gActiveBattler / 2) |= (1 << AI_HEAL_SLEEP);
                 shouldUse = TRUE;
             }
-            if (itemEffects[3] & ITEM3_POISON && (gBattleMons[gActiveBattler].status1 & STATUS1_POISON 
+            if (itemEffects[3] & ITEM3_POISON && (gBattleMons[gActiveBattler].status1 & STATUS1_POISON
                                                || gBattleMons[gActiveBattler].status1 & STATUS1_TOXIC_POISON))
             {
                 *(gBattleStruct->AI_itemFlags + gActiveBattler / 2) |= (1 << AI_HEAL_POISON);