adjust some protection levels

Bonk/Edge.cs

@@ -2,7 +2,7 @@
 
 namespace MoonTools.Core.Bonk
 {
-    public struct Edge
+    internal struct Edge
     {
         public float distance;
         public Vector2 normal;

Bonk/SpatialHash.cs

@@ -16,7 +16,7 @@ namespace MoonTools.Core.Bonk
             this.cellSize = cellSize;
         }
 
-        public (int, int) Hash(int x, int y)
+        private (int, int) Hash(int x, int y)
         {
             return ((int)Math.Floor((float)x / cellSize), (int)Math.Floor((float)y / cellSize));
         }