fixed similarterm

Author: Alessandro

src/TermInterface.jl

@@ -91,10 +91,10 @@ and `metadata` as the metadata. By default this will execute `head(args...)`.
 `x` parameter can also be a `Type`.
 """
 similarterm(x, head, args, symtype=nothing; metadata=nothing) = 
-    similarterm(typeof(x), head, args, symtype; metadata=nothing)
+    similarterm(typeof(x), head, args, symtype; metadata=metadata)
 
 similarterm(x, head, args; metadata=nothing) = 
-    similarterm(typeof(x), head, args; metadata=nothing)
+    similarterm(typeof(x), head, args; metadata=metadata)
 
 
 similarterm(x::Type{Expr}, head, args, symtype=nothing; metadata=nothing) = Expr(head, args...)