v9 - Child theme templates

This release focuses on implementing the page templates in the Child theme. The work was broken down into a large number of PRs in order to keep things organized and facilitate code review:

What's Changed

• Pathfinder PR for child theme templates by @matt-bernhardt in #41
• Results of PHPCBF automated cleaning by @matt-bernhardt in #42
• Updated whitelist for navwalker library by @matt-bernhardt in #44
• Resolve or whitelist content escaping problems by @matt-bernhardt in #43
• Standardize file comment tags, add namespaces by @matt-bernhardt in #45
• Rename postHead partial to title-banner by @matt-bernhardt in #47
• Update namespace where needed by @matt-bernhardt in #48
• Update child theme to use parent's breadcrumb function by @matt-bernhardt in #49
• Update domain names now that contract is signed by @matt-bernhardt in #51
• Implement content_nav function in parent and child themes by @matt-bernhardt in #50
• Add functions to child theme by @matt-bernhardt in #52
• Remove isRoot / pageRoot calculations by @matt-bernhardt in #53

Full Changelog: v8...v9