Substantially improve behavior of nested Table & Collection Nodes

This ensures memory cleanup happens correctly and introduces a new test project
to support developing new features while stressing tough use cases for correctness.

examples/HorizontalWithinVerticalScrolling/Sample/RandomCoreGraphicsNode.m

@@ -38,6 +38,7 @@
   CGGradientDrawingOptions drawingOptions;
   CGContextDrawLinearGradient(ctx, gradient, CGPointZero, CGPointMake(bounds.size.width, bounds.size.height), drawingOptions);
   
+  CGGradientRelease(gradient);
   CGColorSpaceRelease(colorSpace);
 }