Make sure json output array order is consistent

The source of the "contractDependencies" value was an std::map, thus
order was more or less random.

libsolidity/ast/ASTJsonConverter.cpp

@@ -27,6 +27,9 @@
 #include <libdevcore/UTF8.h>
 #include <boost/algorithm/string/join.hpp>
 
+#include <vector>
+#include <algorithm>
+
 using namespace std;
 using namespace langutil;
 
@@ -259,7 +262,7 @@ bool ASTJsonConverter::visit(ContractDefinition const& _node)
 		make_pair("fullyImplemented", _node.annotation().unimplementedFunctions.empty()),
 		make_pair("linearizedBaseContracts", getContainerIds(_node.annotation().linearizedBaseContracts)),
 		make_pair("baseContracts", toJson(_node.baseContracts())),
-		make_pair("contractDependencies", getContainerIds(_node.annotation().contractDependencies)),
+		make_pair("contractDependencies", getContainerIds(_node.annotation().contractDependencies, true)),
 		make_pair("nodes", toJson(_node.subNodes())),
 		make_pair("scope", idOrNull(_node.scope()))
 	});

libsolidity/ast/ASTJsonConverter.h

@@ -29,6 +29,8 @@
 #include <json/json.h>
 #include <ostream>
 #include <stack>
+#include <vector>
+#include <algorithm>
 
 namespace langutil
 {
@@ -148,15 +150,23 @@ private:
 		return _node.id();
 	}
 	template<class Container>
-	static Json::Value getContainerIds(Container const& container)
+	static Json::Value getContainerIds(Container const& _container, bool _order = false)
 	{
-		Json::Value tmp(Json::arrayValue);
-		for (auto const& element: container)
+		std::vector<int> tmp;
+
+		for (auto const& element: _container)
 		{
 			solAssert(element, "");
-			tmp.append(nodeId(*element));
+			tmp.push_back(nodeId(*element));
 		}
-		return tmp;
+		if (_order)
+			std::sort(tmp.begin(), tmp.end());
+		Json::Value json(Json::arrayValue);
+
+		for (int val: tmp)
+			json.append(val);
+
+		return json;
 	}
 	static Json::Value typePointerToJson(TypePointer _tp, bool _short = false);
 	static Json::Value typePointerToJson(boost::optional<FuncCallArguments> const& _tps);