tile animation: synthesize ANIMBIT when saving (for compatibility)

Also, add some safety checks in case Tiles.get() is called with an out-of-range tile number.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@739 d9718cc8-9f43-0410-858b-315f434eb58c

src/micropolisj/engine/Micropolis.java

@@ -1964,7 +1964,9 @@ public class Micropolis
 		{
 			for (int y = 0; y < DEFAULT_HEIGHT; y++)
 			{
-				map[y][x] = (char) dis.readShort();
+				int z = dis.readShort();
+				z &= ~(2048);         // clear ANIMBIT on import
+				map[y][x] = (char) z;
 			}
 		}
 	}
@@ -1976,7 +1978,11 @@ public class Micropolis
 		{
 			for (int y = 0; y < DEFAULT_HEIGHT; y++)
 			{
-				out.writeShort(map[y][x]);
+				int z = map[y][x];
+				if (isAnimated(z)) {
+					z |= 2048;   //synthesize ANIMBIT on export
+				}
+				out.writeShort(z);
 			}
 		}
 	}

src/micropolisj/engine/TileConstants.java

@@ -283,7 +283,7 @@ public class TileConstants
 	public static boolean isAnimated(int tile)
 	{
 		TileSpec spec = Tiles.get(tile & LOMASK);
-		return spec.animNext != null;
+		return spec != null && spec.animNext != null;
 	}
 
 	//used by setFire()

src/micropolisj/engine/Tiles.java

@@ -50,6 +50,11 @@ public class Tiles
 
 	public static TileSpec get(int tileNumber)
 	{
+		if (tileNumber >= 0 && tileNumber < tiles.length) {
 			return tiles[tileNumber];
 		}
+		else {
+			return null;
+		}
+	}
 }