Add convenience properties

Author: STREGA

Sources/GameMath/2D Types/2D Physics/Line2D.swift

@@ -16,6 +16,11 @@ public struct Line2D: Sendable {
 }
 
 public extension Line2D {
+    @inlinable
+    var direction: Direction2 {
+        return Direction2(from: p1, to: p2)
+    }
+    
     func pointNear(_ p: Position2) -> Position2 {
         let ab = p2 - p1
         let ap = p - p1

Sources/GameMath/3D Types/3D Physics/Line3D.swift

@@ -18,6 +18,11 @@ public struct Line3D: Sendable {
 }
 
 public extension Line3D {
+    @inlinable
+    var direction: Direction3 {
+        return Direction3(from: p1, to: p2)
+    }
+    
     @inlinable
     func pointNear(_ p: Position3) -> Position3 {
         let ab = p2 - p1

Sources/GameMath/3D Types/Size3.swift

@@ -94,6 +94,18 @@ public extension Size3 {
             self.y = newValue.y
         }
     }
+    
+    
+    @inlinable
+    var xz: Size2 {
+        get {
+            return Size2(x, z)
+        }
+        set {
+            self.x = newValue.x
+            self.z = newValue.y
+        }
+    }
 }
 
 public extension Size3 {