Fixed foundation class Block not taking -1 as a valid data value (used for wildcard matching of the data value).

src/main/java/com/sk89q/worldedit/foundation/Block.java

@@ -156,8 +156,8 @@ public class Block implements TileEntityBlock {
                             + data + " given)");
         }
         
-        if (data < 0) {
-            throw new IllegalArgumentException("Can't have a block data value below 0");
+        if (data < -1) {
+            throw new IllegalArgumentException("Can't have a block data value below -1");
         }
         
         this.data = (short) data;
@@ -176,6 +176,16 @@ public class Block implements TileEntityBlock {
         setData(data);
     }
     
+    /**
+     * Returns whether the data value is -1, indicating that this block is to be
+     * used as a wildcard matching block.
+     * 
+     * @return true if the data value is -1
+     */
+    public boolean hasWildcardData() {
+        return getData() == -1;
+    }
+    
     @Override
     public boolean hasNbtData() {
         return getNbtData() != null;