Converted indexing to std::size_t, and fixed the Node templated overloads to properly index any index type (determining what is an index type is a bit of a hack - it should be is_convertible<T, std::size_t> (I think), but I just explicitly wrote down a list)

src/exp.cpp

@@ -10,7 +10,7 @@ namespace YAML
 		unsigned ParseHex(const std::string& str, const Mark& mark)
 		{
 			unsigned value = 0;
-			for(unsigned i=0;i<str.size();i++) {
+			for(std::size_t i=0;i<str.size();i++) {
 				char ch = str[i];
 				int digit = 0;
 				if('a' <= ch && ch <= 'f')