Added new Extent-compatible Clipboard and BlockArrayClipboard classes.

The goal is to replace use of CuboidClipboard with these new classes.

Support for entities, //flip, //rotate, and //distr still needs to be
re-implemented.

DataException was also removed from BaseBlock because The Base(...)
classes should be "dumb" blocks without any validation.

src/bukkit/java/com/sk89q/worldedit/bukkit/DefaultNmsBlock.java

@@ -134,7 +134,7 @@ public class DefaultNmsBlock extends NmsBlock {
     }
 
     @Override
-    public void setNbtData(CompoundTag tag) throws DataException {
+    public void setNbtData(CompoundTag tag) {
         if (tag == null) {
             this.nbtData = null;
         }