Fix errors after SetVar behavior change and let removal

rawgrammar.leg

@@ -1,5 +1,5 @@
 grammar        = -
-               ( d:definition                            { set(d.name, d.expression); }
+               ( d:definition                            { setInTopNamespace(d.name, d.expression); }
                ) + end-of-file
 
 definition     = i:identifier ASSIGN e:expression SEMI?  { Definition.new(name: i, expression: e); }