Add some more __internal__ <-> air logi

Fixes #831

worldedit-core/src/main/java/com/boydti/fawe/object/mask/AirMask.java

@@ -16,4 +16,9 @@ public class AirMask extends BlockMask {
         return new AirMask(getExtent());
     }
 
+    @Override
+    public boolean replacesAir() {
+        return true;
+    }
+
 }

worldedit-core/src/main/java/com/boydti/fawe/object/mask/IdDataMask.java

@@ -37,4 +37,9 @@ public class IdDataMask extends AbstractExtentMask implements ResettableMask {
         return new IdDataMask(getExtent());
     }
 
+    @Override
+    public boolean replacesAir() {
+        return true;
+    }
+
 }

worldedit-core/src/main/java/com/boydti/fawe/object/mask/IdMask.java

@@ -38,4 +38,9 @@ public class IdMask extends AbstractExtentMask implements ResettableMask {
         return new IdMask(getExtent());
     }
 
+    @Override
+    public boolean replacesAir() {
+        return true;
+    }
+
 }