add support for unsigned int

include/mstch/mstch.hpp

@@ -94,7 +94,7 @@ class lambda_t {
 }
 
 using node = boost::make_recursive_variant<
-    std::nullptr_t, std::string, int, double, bool,
+    std::nullptr_t, std::string, int, unsigned int, double, bool,
     internal::lambda_t<boost::recursive_variant_>,
     std::shared_ptr<internal::object_t<boost::recursive_variant_>>,
     std::map<const std::string, boost::recursive_variant_>,

src/visitor/render_node.hpp

@@ -26,6 +26,10 @@ class render_node: public boost::static_visitor<std::string> {
     return std::to_string(value);
   }
 
+  std::string operator()(const unsigned int& value) const {
+    return std::to_string(value);
+  }
+
   std::string operator()(const double& value) const {
     std::stringstream ss;
     ss << value;