Minor parser changes

[tobim]

No description provided.

[mavam]

I'm reluctant to change the semantics of % in this fashion, because we are using the parser also in other parts of the code where we do not want a trailing RHS. Instead, I suggest to explicitly identify the places where we want to allow trailing commas and change

x % y

to

(x % y) >> ~y

This way we retain maximum flexibility at the framework level.

[mavam]

Looks better now.

I think we want the same semantics for our data parser, in particular for vector, set, and table types.