Continued to implement standard serializing interpreters

Everything that is interpreted also has to move out of detail namespace,
because it might have to be specialized for a database connector

tests/InterpretTest.cpp

@@ -36,8 +36,10 @@ int main()
 {
 	TabSample t;
 
-	interpret(t.alpha, printer);
-	interpret(t.alpha = 7, printer);
+	interpret(t.alpha, printer).flush();
+	interpret(t.alpha = 7, printer).flush();
+	sqlpp::text_operand o = {"kaesekuchen"};
+	interpret(t.beta + "kaesekuchen", printer).flush();
 
 	return 0;
 }

tests/MockDb.h

@@ -39,11 +39,21 @@ public:
 		{}
 
 		template<typename T>
-			std::ostream& operator<<(const T& t)
+			std::ostream& operator<<(T t)
 			{
 				return _os << t;
 			}
 
+		void flush()
+		{
+			_os << std::endl;
+		}
+
+		std::string escape(std::string arg)
+		{
+			return arg;
+		}
+
 		std::ostream& _os;
 	};