resolves #507 customize toc inside body content
Merge pull request #550 from mojavelinux/toc-styles

resolves #507 customize toc inside body content
resolves #551 strip leading separator(s) on section id if idprefix is blank

- make section id sub regex a constant
- capture all entities, not just numeric ones
Merge pull request #552 from mojavelinux/strip-leading-separator-in-sectid

resolves #551 strip leading separator(s) on section id if idprefix is blank