Rebuild theme

[mmistakes]

So Simple v3 is a major rewrite of the entire theme. The most notable changes are summarized below:

Global Changes

• Create theme gem
• Properly support site.baseurl and site.url by leveraging absolute_url and relative_url
• Freshen up look and feel, rebuilding with CSS grid and flexbox
• Improve author (owner) links
• Improve adding custom links to footer
• Allow footer copyright to be changed via site.copyright
• Improve adding custom Google fonts
• Add hooks for dropping in custom code
• Add read time support
• Support MathJax
• i18n text strings
• Add grid/list view for items
• Upgrade to Font Awesome 5
• Add jekyll-paginate support
• Replace Jekyll Simple Search with Lunr.js
• Improve syntax highlighting styling, support linenos
• Enable/disable excerpts with show_excerpts flag
• Improve responsive menu

Layout & Include Changes

• Improve parity with Jekyll's default theme layouts found in Minima:
  • Create default layout
  • Create home that shows n recent posts or all posts with pagination
  • Create post and page layouts
• Create posts archive layout
• Create category and tag archive layouts (GitHub Pages compatible)
• Create category and tag archive layouts for jekyll-archives plugin
• Create singular taxonomy page layout (e.g. page that shows all posts in category articles)
• Create search layout
• Add Microformats markup
• Replace open-graph include with jekyll-seo-tag
• Add responsive embed helper
• Add table of contents helper

Documentation Changes

• Create CHANGELOG
• Add installation guide (ruby gem, remote theme, etc.)
• Document config variable name changes
• Document open-graph changes
• Document image path changes
• Document layout changes
• Add suggested image sizes for: site.logo, page.image, author avatar, etc.
• Document responsive embed helper
• Document table of contents helper
• Add migration guide for v2 to v3
• Add links to demo pages (preview and source links)

Development Changes

• Reduce JavaScript dependencies
• Replace Grunt tasks with npm run scripts

Housekeeping

• Add stale bot
• Update GitHub issue labels
• Update GitHub issue template
• Migrate gh-pages content to docs/

Preview

Refreshed Post Layout

NEW Grid View

NEW List View

NEW Tags Layout

Related: #58, #91, #224, #247, #249, #196, #198, #216, #241, #253