added Distance function, quick fix for Neighbors function

HexTile.cpp

@@ -39,3 +39,11 @@ void AHexTile::FillCornersArray()
 		Corners.Emplace(Corner(i + 1));
 	}
 }
+
+int32 AHexTile::Distance(AHexTile* ToHex)
+{
+	int32 CubeS1 = -this->Q - this->R;
+	int32 CubeS2 = -ToHex->Q - ToHex->R;
+
+	return (abs(this->Q - ToHex->Q) + abs(this->R - ToHex->R) + abs(CubeS1 - CubeS2)) / 2;
+}