Add jekyll-thumbnail-filter to plugins list
Use relative path for `path` Liquid variable in Documents
Keep backwards compatibility

Re-add `relative_path` Liquid variable too keep compatibility
Generalize Utils#slugify for any scripts

It replaces any non alphanumeric glyphs by an hyphen.
Incremental regeneration
Refinements
Add regenerate front-matter variable
Fix failing tests
Implement @mattr-'s suggestions
Add clean command
Handle path overrides
Add --no-metadata option
Use site.in_source_dir
Implement more suggestions
Add unit and cucumber tests
compare resulting data in jsonify test
refactor #as_liquid
reduce nesting of #as_liquid
Perform less expensive operation first
Add lots more unit tests