Ignore caps in comments (on their own lines only)

This ignores caps-ing in comments like: 

```sql
-- Select username and permissions mask for user id 77.
SELECT u.username, u.permission_mask FROM SITE_USER AS U
       WHERE u.id = 77;
```

For now this doesn't handle other comment types (multi-line and normal `/* comment */` on a single line). Adding them would require modifying only the is-commentp predicate to detect this.