[minor] added/clarified some documents to better document the code

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/trunk/supertuxkart@2424 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/items/powerup.cpp

@@ -248,9 +248,9 @@ void Powerup::hitBonusBox(int n, const Item &item, int add_info)
 
     // Otherwise (server or no network): determine powerup randomly
 
-    //rand() is moduled by POWERUP_MAX - 1 - 2 because because we have to
-    //exclude the anvil and the parachute, but later we have to add 1 to prevent
-    //having a value of 0 since that isn't a valid powerup.
+    //(POWERUP_MAX - 1) is the last valid id. We substract 2 because because we have to
+    //exclude the anvil and the parachute which are handled above, but later we
+    //have to add 1 to prevent having a value of 0 since that isn't a valid powerup.
     PowerupType newC;
     while(true)
     {

src/items/powerup_manager.hpp

@@ -32,7 +32,7 @@ class ssgEntity;
 enum PowerupType {POWERUP_NOTHING,
                   POWERUP_BUBBLEGUM, POWERUP_CAKE,
                   POWERUP_BOWLING, POWERUP_ZIPPER,
-                  POWERUP_PARACHUTE, POWERUP_ANVIL,
+                  POWERUP_PARACHUTE, POWERUP_ANVIL, //powerup.cpp assumes these two come last
                   POWERUP_MAX};
 
 class PowerupManager