impletements the usage: metta [-h] [--version | MeTTa script] functio…

…ns so we can also do trueagi-io/hyperon-experimental#803

.Attic/metta_lang/metta_eval.pl

@@ -412,6 +412,10 @@
     ignore(Type=RetType),
     eval_args(Eq,Type,Depth,Self,X, Res).
 
+% simple version of Minimal MeTTa's `metta` function
+eval_20(Eq,_Maybe_TODO_RetType,Depth,Self,['metta',Eval,RetType,Other],Result):-!,
+    into_space(Depth,Self,Other,Space),
+    eval_args(Eq,RetType,Depth,Space,Eval,Result).
 
 
 /* Function takes list of atoms (first argument), variable (second argument) and filter predicate (third argument) and returns list with items which passed filter.