Merge pull request #561 from Dmitry-Me/unlinkedElementsAssertions

Unlinked nodes assertions

tinyxml2.cpp

@@ -1994,6 +1994,7 @@ XMLDocument::~XMLDocument()
 
 void XMLDocument::MarkInUse(XMLNode* node)
 {
+	TIXMLASSERT(node);
 	TIXMLASSERT(node->_parent == 0);
 
 	for (int i = 0; i < _unlinked.Size(); ++i) {

tinyxml2.h

@@ -265,8 +265,8 @@ public:
     }
 
 	void SwapRemove(int i) {
-        TIXMLASSERT(i >= 0);
-		TIXMLASSERT(i < _size);
+		TIXMLASSERT(i >= 0 && i < _size);
+		TIXMLASSERT(_size > 0);
 		_mem[i] = _mem[_size - 1];
 		--_size;
 	}