(svn r6049) -Codechange: forgot EngineRenew in r6047

-Codechange: cleaned up the EngineRenew code a bit (coding style mostly)
-Codechange: forgot the correct comment in station_cmd
-Codechange: move pool-stuff to engine.h, like we always do

openttd.h

@@ -48,6 +48,7 @@ typedef uint32 SpriteID;    ///< The number of a sprite, without mapping bits an
 typedef uint32 PalSpriteID; ///< The number of a sprite plus all the mapping bits and colortables
 typedef uint32 CursorID;
 typedef uint16 EngineID; ///< All enginenumbers should be of this type
+typedef uint16 EngineRenewID;
 typedef uint16 UnitID;   ///< All unitnumber stuff is of this type (or anyway, should be)
 
 typedef uint32 WindowNumber;