Fixed wrong pager, fixes #655

$startnum returned by the pager starts with 1, but it needs to be 0 instead.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #655
| License       | MIT
| Doc PR        | --