ENH: use simpler boundBox handling

- use default initialize boundBox instead of invertedBox
- reset() instead of assigning from invertedBox
- extend (three parameter version) and grow method
- inflate(Random) instead of extend + re-assigning

src/OpenFOAM/algorithms/AABBTree/AABBTree.C

@@ -195,10 +195,10 @@ void Foam::AABBTree<Type>::createBoxes
     // Assign the objects to min or max bin
 
     DynamicList<label> minBinObjectIDs(objectIDs.size());
-    treeBoundBox minBb(boundBox::invertedBox);
+    treeBoundBox minBb;
 
     DynamicList<label> maxBinObjectIDs(objectIDs.size());
-    treeBoundBox maxBb(boundBox::invertedBox);
+    treeBoundBox maxBb;
 
     for (const label objI : objectIDs)
     {