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/field_message_box.c

@@ -105,7 +105,7 @@ static bool8 ForceShowFieldAutoScrollMessage(const u8 *str)
     return TRUE;
 }
 
-// Same as ShowFieldMessage, but instead of accepting a 
+// Same as ShowFieldMessage, but instead of accepting a
 // string arg it just prints whats already in gStringVar4
 bool8 ShowFieldMessageFromBuffer(void)
 {