lang/php: replace ac-php with phpactor.el

phpactor is superior to phpctags, though it requires more setup.

phpactors.el is superior to ac-php, though it is in alpha.

modules/lang/php/autoload.el

@@ -2,6 +2,17 @@
 
 (defvar +php-composer-conf (make-hash-table :test 'equal))
 
+;;;###autoload
+(defun +php-company-backend (command &optional arg &rest _ignored)
+  "A delegating company-backend that uses `company-phpactor' if phpactor is
+available and installed, or `php-extras-company' otherwise."
+  (cond ((and (require 'company-phpactor nil t)
+              (ignore-errors (phpactor-find-executable)))
+         (company-phpactor command arg))
+        ((and (require 'php-extras nil t)
+              (file-exists-p (concat php-extras-eldoc-functions-file ".el")))
+         (php-extras-company command arg))))
+
 ;;;###autoload
 (defun +php-composer-conf (&optional project-root refresh-p)
   "Retrieve the contents of composer.json as an alist. If REFRESH-P is non-nil