psql and ROLES

Hi,

I'm currently working on syncing psql's tab-complete code with the docs
especially wrt ROLES. while working on this I noticed the following things:

*) there is no backslash command for getting a list of Roles (like \du &
\dg for Users and Groups) - I'm considering using \dr for that - does
that sound sensible ?

*) the new connectionlimit code allows for negative Limits (beside -1)
like this:

playground=# CREATE ROLE testrole LOGIN CONNECTION LIMIT -999999999;
CREATE ROLE

that doesn't strike me as that useful (and it is not clear what that
should mean anyway because such a user can still login) - so maybe we
should reject that (and create a sensible upper bound for that too)

Stefan