Fixed several bugs from the new file i/o setup.

In particular:
1. Windows CR/LF weren't read properly (issue #11)
2. Scanning wasn't reading EOF properly
3. Documents may be empty (this was old, I think)
Also fixed some VS2008 warnings on /W4.

src/node.cpp

@@ -37,6 +37,10 @@ namespace YAML
 	{
 		Clear();
 
+		// an empty node *is* a possibility
+		if(pScanner->empty())
+			return;
+
 		// save location
 		m_line = pScanner->peek().line;
 		m_column = pScanner->peek().column;