Linter & Parser Improvements + Unicode

Added

• linter: adding-field-with-default now allows more cases (#652).

  alter table t add column c text[] default array[]::text[];
  alter table t add column c timestamptz default current_timestamp;
  
  -- const/non-volatile binary expressions are also allowed
  alter table t add column c timestamptz default now() - interval '100 years';

Fixed

• parser: parse materialized views using a paren select (#651).

  The following now parses:

  create materialized view v
  as (select * from t);

Changed

• cli now uses unicode for snippet annotations (#654).