fix wrong m_renderCount value after calling CKLBNode::setRenderSlotCount(1)

CKLBNode *node = ...;
node->setRenderSlotCount(2);
node->setRenderSlotCount(1);
// expected: m_renderCount == 1
// actual: m_renderCount == 0
Merge pull request #51 from zaki50/fix_renderCount_bug

fix wrong m_renderCount value after calling CKLBNode::setRenderSlotCount(1)