Implements static, server side generated pagination.

- Updated topic and category templates for a pagination bar with plain HTML <a> links
- Requires a corresponding change in nodebb core. See https://github.com/baerrus/NodeBB, branch seo-0.5.7
Merge branch 'seo-nodebb-0.5.7' of https://github.com/baerrus/nodebb-theme-lavender into seo-nodebb-0.5.7

resolved Conflicts:
	templates/partials/paginator.tpl