Tiny first step in removing ArgsTuple and other tuples and replace by…

… std::array.

fix echelon level to 2. There is no plan to ever implement higher levels in this way and version. Not quite supported anyways.
using array probably not using much more space and probably even faster than use of tuples.
recursion can be replaced by loops which are typically faster.

src/core/config.h

@@ -34,7 +34,7 @@
 //#define PIRANHA_VISIBLE __attribute__ ((visibility("default")))
 //#endif
 
-#define PIRANHA_MAX_ECHELON_LEVEL (1)
+#define PIRANHA_MAX_ECHELON_LEVEL (2)
 
 
 #endif

src/core/psym.h

@@ -466,6 +466,13 @@ namespace piranha
 
 		return vectorPsym;
 	}
+
+	using EvalVectors = std::array<std::vector<std::vector<double>> &, PIRANHA_MAX_ECHELON_LEVEL>; // we don't use and/or intend to use anything higher than echeclonLevel 2
+	using ArgsVector = std::array<VectorPsym, PIRANHA_MAX_ECHELON_LEVEL>; 
+	//EvalVectors args2EvalVectors(ArgsTupleType const & argdTuple)
+	//{
+
+	//}
 }
 
 #pragma warning (pop)