Fix multiple low priority issues

closes #12, closes #80, closes #95, closes #96, closes #99

- Issue #12: Set tp_new to NULL for GridPoint and GridPointState to prevent instantiation from Python
- Issue #80: Renamed Caption.size to Caption.font_size for semantic clarity
- Issue #95: Fixed UICollection repr to show actual derived types instead of generic UIDrawable
- Issue #96: Added extend() method to UICollection for API consistency with UIEntityCollection
- Issue #99: Exposed read-only properties for Texture (sprite_width, sprite_height, sheet_width, sheet_height, sprite_count, source) and Font (family, source)

All issues have corresponding tests that verify the fixes work correctly.

tests/issue_12_gridpoint_instantiation_test.py

@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+"""
+Test for Issue #12: Forbid GridPoint/GridPointState instantiation
+
+This test verifies that GridPoint and GridPointState cannot be instantiated
+directly from Python, as they should only be created internally by the C++ code.
+"""
+
+import mcrfpy
+import sys
+
+def test_gridpoint_instantiation():
+    """Test that GridPoint and GridPointState cannot be instantiated"""
+    print("=== Testing GridPoint/GridPointState Instantiation Prevention (Issue #12) ===\n")
+    
+    tests_passed = 0
+    tests_total = 0
+    
+    # Test 1: Try to instantiate GridPoint
+    print("--- Test 1: GridPoint instantiation ---")
+    tests_total += 1
+    try:
+        point = mcrfpy.GridPoint()
+        print("✗ FAIL: GridPoint() should not be allowed")
+    except TypeError as e:
+        print(f"✓ PASS: GridPoint instantiation correctly prevented: {e}")
+        tests_passed += 1
+    except Exception as e:
+        print(f"✗ FAIL: Unexpected error: {e}")
+    
+    # Test 2: Try to instantiate GridPointState
+    print("\n--- Test 2: GridPointState instantiation ---")
+    tests_total += 1
+    try:
+        state = mcrfpy.GridPointState()
+        print("✗ FAIL: GridPointState() should not be allowed")
+    except TypeError as e:
+        print(f"✓ PASS: GridPointState instantiation correctly prevented: {e}")
+        tests_passed += 1
+    except Exception as e:
+        print(f"✗ FAIL: Unexpected error: {e}")
+    
+    # Test 3: Verify GridPoint can still be obtained from Grid
+    print("\n--- Test 3: GridPoint obtained from Grid.at() ---")
+    tests_total += 1
+    try:
+        grid = mcrfpy.Grid(10, 10)
+        point = grid.at(5, 5)
+        print(f"✓ PASS: GridPoint obtained from Grid.at(): {point}")
+        print(f"  Type: {type(point).__name__}")
+        tests_passed += 1
+    except Exception as e:
+        print(f"✗ FAIL: Could not get GridPoint from Grid: {e}")
+    
+    # Test 4: Verify GridPointState can still be obtained from GridPoint
+    print("\n--- Test 4: GridPointState obtained from GridPoint ---")
+    tests_total += 1
+    try:
+        # GridPointState is accessed through GridPoint's click handler
+        # Let's check if we can access point properties that would use GridPointState
+        if hasattr(point, 'walkable'):
+            print(f"✓ PASS: GridPoint has expected properties")
+            print(f"  walkable: {point.walkable}")
+            print(f"  transparent: {point.transparent}")
+            tests_passed += 1
+        else:
+            print("✗ FAIL: GridPoint missing expected properties")
+    except Exception as e:
+        print(f"✗ FAIL: Error accessing GridPoint properties: {e}")
+    
+    # Test 5: Try to call the types directly (alternative syntax)
+    print("\n--- Test 5: Alternative instantiation attempts ---")
+    tests_total += 1
+    all_prevented = True
+    
+    # Try various ways to instantiate
+    attempts = [
+        ("mcrfpy.GridPoint.__new__(mcrfpy.GridPoint)", 
+         lambda: mcrfpy.GridPoint.__new__(mcrfpy.GridPoint)),
+        ("type(point)()", 
+         lambda: type(point)() if 'point' in locals() else None),
+    ]
+    
+    for desc, func in attempts:
+        try:
+            if func:
+                result = func()
+                print(f"✗ FAIL: {desc} should not be allowed")
+                all_prevented = False
+        except (TypeError, AttributeError) as e:
+            print(f"  ✓ Correctly prevented: {desc}")
+        except Exception as e:
+            print(f"  ? Unexpected error for {desc}: {e}")
+    
+    if all_prevented:
+        print("✓ PASS: All alternative instantiation attempts prevented")
+        tests_passed += 1
+    else:
+        print("✗ FAIL: Some instantiation attempts succeeded")
+    
+    # Summary
+    print(f"\n=== SUMMARY ===")
+    print(f"Tests passed: {tests_passed}/{tests_total}")
+    
+    if tests_passed == tests_total:
+        print("\nIssue #12 FIXED: GridPoint/GridPointState instantiation properly forbidden!")
+    else:
+        print("\nIssue #12: Some tests failed")
+    
+    return tests_passed == tests_total
+
+def run_test(runtime):
+    """Timer callback to run the test"""
+    try:
+        # First verify the types exist
+        print("Checking that GridPoint and GridPointState types exist...")
+        print(f"GridPoint type: {mcrfpy.GridPoint}")
+        print(f"GridPointState type: {mcrfpy.GridPointState}")
+        print()
+        
+        success = test_gridpoint_instantiation()
+        print("\nOverall result: " + ("PASS" if success else "FAIL"))
+    except Exception as e:
+        print(f"\nTest error: {e}")
+        import traceback
+        traceback.print_exc()
+        print("\nOverall result: FAIL")
+    
+    sys.exit(0)
+
+# Set up the test scene
+mcrfpy.createScene("test")
+mcrfpy.setScene("test")
+
+# Schedule test to run after game loop starts
+mcrfpy.setTimer("test", run_test, 100)