Timber 2.x

[acobster]

This is NOT ready to go and should not be merged yet, but putting this here so we can at least see the full changeset.

Relevant guides:

• Timber 2.0 upgrade guide
• Timber Class Maps

[rhendrickson-sc]

@sdunham Leaving this comment here at your direction: wanted to give a heads up that I get some deprecation notices from Timber on a fresh project setup using this branch.

• views/partials/blocks/nav.twig needs to have all its item.get_children function calls changed to item.children.
• views/partials/blocks/subnav.twig needs to have all its item.get_children function calls changed to item.children.
• views/partials/hero.twig needs to have all its single Image function call changed to get_image.