Let check return nonzero exit status on failure (fixes #198)
Let stale check honor pruner excludes (fixes #203)
Support HTML_TOC Redcarpet renderer (fixes #222)
Merge pull request #231 from ddfreyne/bug-stale-check-should-honor-prune-exclude

Let stale check honor pruner excludes
Merge pull request #232 from ddfreyne/bug-redcarpet-html-toc-crash

Support HTML_TOC Redcarpet renderer
Merge pull request #230 from ddfreyne/bug-check-exit-status

Let check return nonzero exit status on failure
Update release notes for 3.5.1
Merge branch 'release-3.5.x' of github.com:nanoc/nanoc into release-3.5.x
Merge branch 'release-3.5.x'