Rename file BoundingBox to BoundingBox2 and remove dedicated namespace for it

BoundingBox2.cs

@@ -1,6 +1,6 @@
 using System.Numerics;
 
-namespace BoundingBox
+namespace Quadtree
 {
     public enum IntersectionType { Contains, Intersects, Disjoint }
 

IWorldObject.cs

@@ -1,5 +1,4 @@
-using BoundingBox;
-using System.Numerics;
+using System.Numerics;
 
 namespace Quadtree
 {

Quadtree.cs

@@ -1,6 +1,4 @@
-using BoundingBox;
-using System.Collections.Generic;
-using System.Numerics;
+using System.Numerics;
 
 namespace Quadtree
 {

QuadtreeQuery.cs

@@ -1,6 +1,4 @@
-using BoundingBox;
-
-namespace Quadtree
+namespace Quadtree
 {
     internal struct QuadtreeQuery
     {