Printing of functions with one argument

[NeuralCoder3]

Functions with only one argument are printed without brackets:

    .cn return_178710 _178716: [%mem.M, .Idx 4294967296]  = {
        return_178715 _178716
    };

In cases like the one above, this is correct.
But this hinders readability in some cases (name_num vs name _num) and prevents simply adding/printing a filter @filter at the end.

In some cases like continuation arguments, the invalid code

.cn fun_name .Cn ... = ...

is generated.

Suggestion: always print brackets.

[leissa]

A related thing is the following oddity: The FE currently uses the name _ as magic name to indicate that we are not interested in this entity and will happily name many things internally as _. But on top of that Def::unique_name() will generate a name consisting of Def::name() + _ + Def::gid(). For this reasons some variables end up named like __12345 (note the double underscore) in the output Oo
I think the output could be improved if we used a different separator in Def::unique_name(). Then, we would have sth like this:

.cn name_num.23 num.42: T

or

.cn name_num.23 .42: T

or

.cn name_num.23 _.42: T

This should mitigate at least some of the complaints. Now, using . doesn't really work. We would have to agree on a different separator. This was just an example to bring the point (pun intented XD) across.