Fix Entity property setters and PyVector implementation

Fixed the 'new style getargs format' error in Entity property setters by:
- Implementing PyObject_to_sfVector2f/2i using PyVector::from_arg
- Adding proper error checking in Entity::set_position
- Implementing PyVector get_member/set_member for x/y properties
- Fixing PyVector::from_arg to handle non-tuple arguments correctly

Now Entity.pos and Entity.sprite_number setters work correctly with
proper type validation.

tests/entity_property_setters_test.py

@@ -0,0 +1,99 @@
+#!/usr/bin/env python3
+"""
+Test for Entity property setters - fixing "new style getargs format" error
+
+Verifies that Entity position and sprite_number setters work correctly.
+"""
+
+def test_entity_setters(timer_name):
+    """Test that Entity property setters work correctly"""
+    import mcrfpy
+    
+    print("Testing Entity property setters...")
+    
+    # Create test scene and grid
+    mcrfpy.createScene("entity_test")
+    ui = mcrfpy.sceneUI("entity_test")
+    
+    # Create grid with texture
+    texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+    grid = mcrfpy.Grid(10, 10, texture, (10, 10), (400, 400))
+    ui.append(grid)
+    
+    # Create entity
+    initial_pos = mcrfpy.Vector(2.5, 3.5)
+    entity = mcrfpy.Entity(initial_pos, texture, 5, grid)
+    grid.entities.append(entity)
+    
+    print(f"✓ Created entity at position {entity.pos}")
+    
+    # Test position setter with Vector
+    new_pos = mcrfpy.Vector(4.0, 5.0)
+    try:
+        entity.pos = new_pos
+        assert entity.pos.x == 4.0, f"Expected x=4.0, got {entity.pos.x}"
+        assert entity.pos.y == 5.0, f"Expected y=5.0, got {entity.pos.y}"
+        print(f"✓ Position setter works with Vector: {entity.pos}")
+    except Exception as e:
+        print(f"✗ Position setter failed: {e}")
+        raise
+    
+    # Test position setter with tuple (should also work via PyVector::from_arg)
+    try:
+        entity.pos = (7.5, 8.5)
+        assert entity.pos.x == 7.5, f"Expected x=7.5, got {entity.pos.x}"
+        assert entity.pos.y == 8.5, f"Expected y=8.5, got {entity.pos.y}"
+        print(f"✓ Position setter works with tuple: {entity.pos}")
+    except Exception as e:
+        print(f"✗ Position setter with tuple failed: {e}")
+        raise
+    
+    # Test draw_pos setter (collision position)
+    try:
+        entity.draw_pos = mcrfpy.Vector(3, 4)
+        assert entity.draw_pos.x == 3, f"Expected x=3, got {entity.draw_pos.x}"
+        assert entity.draw_pos.y == 4, f"Expected y=4, got {entity.draw_pos.y}"
+        print(f"✓ Draw position setter works: {entity.draw_pos}")
+    except Exception as e:
+        print(f"✗ Draw position setter failed: {e}")
+        raise
+    
+    # Test sprite_number setter
+    try:
+        entity.sprite_number = 10
+        assert entity.sprite_number == 10, f"Expected sprite_number=10, got {entity.sprite_number}"
+        print(f"✓ Sprite number setter works: {entity.sprite_number}")
+    except Exception as e:
+        print(f"✗ Sprite number setter failed: {e}")
+        raise
+    
+    # Test invalid position setter (should raise TypeError)
+    try:
+        entity.pos = "invalid"
+        print("✗ Position setter should have raised TypeError for string")
+        assert False, "Should have raised TypeError"
+    except TypeError as e:
+        print(f"✓ Position setter correctly rejects invalid type: {e}")
+    except Exception as e:
+        print(f"✗ Unexpected error: {e}")
+        raise
+    
+    # Test invalid sprite number (should raise TypeError)
+    try:
+        entity.sprite_number = "invalid"
+        print("✗ Sprite number setter should have raised TypeError for string")
+        assert False, "Should have raised TypeError"
+    except TypeError as e:
+        print(f"✓ Sprite number setter correctly rejects invalid type: {e}")
+    except Exception as e:
+        print(f"✗ Unexpected error: {e}")
+        raise
+    
+    # Cleanup timer
+    mcrfpy.delTimer("test_timer")
+    
+    print("\n✅ Entity property setters test PASSED - All setters work correctly")
+
+# Execute the test after a short delay to ensure window is ready
+import mcrfpy
+mcrfpy.setTimer("test_timer", test_entity_setters, 100)