Made McRegion reading work.

src/com/sk89q/worldedit/data/ForwardSeekableInputStream.java

@@ -60,7 +60,9 @@ public class ForwardSeekableInputStream extends InputStream {
 
     @Override
     public int read(byte[] b, int off, int len) throws IOException {
-        throw new IOException("Offset not supported for read()");
+        int read = super.read(b, off, len);
+        position += read;
+        return read;
     }
 
     @Override

src/com/sk89q/worldedit/data/McRegionChunkStore.java

@@ -48,11 +48,12 @@ public abstract class McRegionChunkStore extends ChunkStore {
     
     protected McRegionReader getReader(Vector2D pos) throws DataException, IOException {
         String filename = getFilename(pos);
-        if (curFilename.equals(filename)) {
+        if (curFilename != null && curFilename.equals(filename)) {
             return cachedReader;
         }
         InputStream stream = getInputStream(filename);
         cachedReader = new McRegionReader(stream);
+        //curFilename = filename;
         return cachedReader;
     }
 

src/com/sk89q/worldedit/data/McRegionReader.java

@@ -117,8 +117,8 @@ public class McRegionReader {
     public synchronized InputStream getChunkInputStream(Vector2D pos)
             throws IOException, DataException {
 
-        int x = pos.getBlockX();
+        int x = pos.getBlockX() & 31;
-        int z = pos.getBlockZ();
+        int z = pos.getBlockZ() & 31;
         
         if (x < 0 || x >= 32 || z < 0 || z >= 32) {
             throw new DataException("MCRegion file does not contain " + x + "," + z);