New features

• feat/includes: bring up includes folder (#63)
• feat: support load async css
• feat(post): add lazyload for post header thumbnail
• fix(search): escape HTML

Changes

• refactor(head): completely rewritten
• refactor(open-graph): improvements
• refactor(footer): custom_code optimization & copyright rewrite
• ci: set nodejs version to 8 10 12
• refactor(archive): rewrite the generation
• refactor(comment): oprimize disqusjs load
• refactor: better usage of fragment_cache

Bugs fixed

• fix(navbar): use archive_dir instead of 'archives/'
• fix(analytics): change wrong google_site_id in gtags.ejs
• fix(head): canonical_url
• fix(config): wrong position of lazyload_img

BREAKING CHANGES

Requires Hexo 4.0.0 or higher version of Hexo.