Initial work on support for objects whose images span multiple tiles.

Made TileSet an interface.  Throw exceptions for unknown tile or tile
set requests.  General clean-up and documentation.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@427 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/tile/TileManager.java

@@ -1,5 +1,5 @@
 //
-// $Id: TileManager.java,v 1.17 2001/09/28 00:44:31 shaper Exp $
+// $Id: TileManager.java,v 1.18 2001/10/11 00:41:26 shaper Exp $
 
 package com.threerings.media.tile;
 
@@ -39,6 +39,7 @@ public class TileManager
      * @return the tile object, or null if an error occurred.
      */
     public Tile getTile (int tsid, int tid)
+	throws NoSuchTileSetException, NoSuchTileException
     {
 	// the fully unique tile id is the conjoined tile set and tile id
 	int utid = (tsid << 16) | tid;