A "list" is a sequence of more than one "term" nodes, so it shouldn't contain
a single parenthesized node.
Also, a parenthesized "term" rule wasn't handled.
A method call is typically parsed as (obj.meth)(), not as obj.(meth()),
but the latter is good enough for our needs. It's unlikely we'll add a
first-class function support.
.into_inner().next().unwrap() mess will be cleaned up by the next commit.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
