Method removeItemAt

UnitTests/UnitTest_HyperTextBox/HyperTextBox.cpp:638–642

	}

	void HyperTextBox::removeItemAt(size_t _index)
	{
		MYGUI_ASSERT_RANGE(_index, mStackPanel->getChildCount(), "HyperTextBox::removeItemAt");
		WidgetManager::getInstancePtr()->destroyWidget(mStackPanel->getChildAt(_index));
	}

	void HyperTextBox::updateBreakHeight()
	{