various

use vector.add for compatibility with vs-flattened
flush before remember
share meta objects across players
fix wg compatibility

worldedit-core/src/main/java/com/sk89q/worldedit/math/BlockVector3.java

@@ -779,4 +779,9 @@ public abstract class BlockVector3 {
         return "(" + getX() + ", " + getY() + ", " + getZ() + ")";
     }
 
+    //Used by VS fork
+    public BlockVector3 plus(BlockVector3 other) {
+        return add(other);
+    }
+
 }