Reduce snippet dependency

[cshold]

Evolution of #358

• Place all one-time-use snippets inline
• Combined snippets when possible (social media meta tags, collection sorting)
• Exceptions:
  • Social meta tags (Open Graph and Twitter cards) are combined to one snippet
  • Old IE js support (Respond.js, shivs, polyfills)
  • Onboarding markup
  • Handlebars.js templates

This PR also:

• Cleans up search result template to reduce duplicate code
• Updates liquid variables to have spaces between `{{ }}``

cc @carolineschnapp @mpiotrowicz @stevebosworth @fredryk

[mpiotrowicz]

can you add HTML comments denoting the start/end to the old snippets? I think it would go a long way in helping ppl navigate this file.

Eg

// begin mobile nav

[cshold]

👍

[mpiotrowicz]

this is great! Were any of the snippets un-snippified twice? (eg snippet contents appear twice now)

[cshold]

Nope, no un-snippification, aka no reused code that doesn't live in a snippet. I'll give it another once over to make sure that's the case though.