Move required theme files to sage/resources

* Resolves issue with WP only looking one-level deep for templates #1870
* get_template_dir() and related functions now point to sage/resources
* Use collect() when assembling views paths
* Update tree in README

functions.php

@@ -1,87 +0,0 @@
-<?php
-
-/**
- * Do not edit anything in this file unless you know what you're doing
- */
-
-/**
- * Helper function for prettying up errors
- * @param string $message
- * @param string $subtitle
- * @param string $title
- */
-$sage_error = function ($message, $subtitle = '', $title = '') {
-    $title = $title ?: __('Sage &rsaquo; Error', 'sage');
-    $footer = '<a href="https://roots.io/sage/docs/">roots.io/sage/docs/</a>';
-    $message = "<h1>{$title}<br><small>{$subtitle}</small></h1><p>{$message}</p><p>{$footer}</p>";
-    wp_die($message, $title);
-};
-
-/**
- * Ensure compatible version of PHP is used
- */
-if (version_compare('5.6.4', phpversion(), '>=')) {
-    $sage_error(__('You must be using PHP 5.6.4 or greater.', 'sage'), __('Invalid PHP version', 'sage'));
-}
-
-/**
- * Ensure compatible version of WordPress is used
- */
-if (version_compare('4.7.0', get_bloginfo('version'), '>=')) {
-    $sage_error(__('You must be using WordPress 4.7.0 or greater.', 'sage'), __('Invalid WordPress version', 'sage'));
-}
-
-/**
- * Ensure dependencies are loaded
- */
-if (!class_exists('Roots\\Sage\\Container')) {
-    if (!file_exists($composer = __DIR__.'/vendor/autoload.php')) {
-        $sage_error(
-            __('You must run <code>composer install</code> from the Sage directory.', 'sage'),
-            __('Autoloader not found.', 'sage')
-        );
-    }
-    require_once $composer;
-}
-
-/**
- * Sage required files
- *
- * The mapped array determines the code library included in your theme.
- * Add or remove files to the array as needed. Supports child theme overrides.
- */
-array_map(function ($file) use ($sage_error) {
-    $file = "app/{$file}.php";
-    if (!locate_template($file, true, true)) {
-        $sage_error(sprintf(__('Error locating <code>%s</code> for inclusion.', 'sage'), $file), 'File not found');
-    }
-}, ['helpers', 'setup', 'filters', 'admin']);
-
-/**
- * Here's what's happening with these hooks:
- * 1. WordPress initially detects theme in themes/sage
- * 2. Upon activation, we tell WordPress that the theme is actually in themes/sage/resources/views
- * 3. When we call get_template_directory() or get_template_directory_uri(), we point it back to themes/sage
- *
- * We do this so that the Template Hierarchy will look in themes/sage/resources/views for core WordPress themes
- * But functions.php, style.css, and index.php are all still located in themes/sage
- *
- * This is not compatible with the WordPress Customizer theme preview prior to theme activation
- *
- * get_template_directory()   -> /srv/www/example.com/current/web/app/themes/sage
- * get_stylesheet_directory() -> /srv/www/example.com/current/web/app/themes/sage
- * locate_template()
- * ├── STYLESHEETPATH         -> /srv/www/example.com/current/web/app/themes/sage
- * └── TEMPLATEPATH           -> /srv/www/example.com/current/web/app/themes/sage/resources/views
- */
-if (is_customize_preview() && isset($_GET['theme'])) {
-    $sage_error(__('Theme must be activated prior to using the customizer.', 'sage'));
-}
-add_filter('template', function ($stylesheet) {
-    return dirname(dirname($stylesheet));
-});
-if (($sage_views = basename(__DIR__).'/resources/views') !== get_option('template')) {
-    update_option('template', $sage_views);
-    wp_redirect($_SERVER['REQUEST_URI']);
-    exit();
-}