updated `{{embed}}` helper to automatically apply file extensions to code "fences" unless overridden by second parameter.
organized utils into better groups
removed unused regex
testing object helpers
reorganize string helpers
improve foreach helper
remove experimental extract and chapter helpers, add "partial" and "include" helpers
re-add link helper temporarily
generalize some regex utils
organize and improve comments on helpers, rebuild
new expandYAML and expandJSON helpers for debugging
update docs for new helpers, run build, bump and publish to npm