feature/lookup: rewrite dash docset integration

+ Uses alist variable to store config, rather than hooks
+ Added check for installed docsets in +lookup/documentation
+ Set docsets for various language modules (c-mode, c++-mode, css-mode,
  scss-mode, sass-mode, web-mode, go-mode, racket-mode, emacs-lisp-mode,
  js2-mode, rjsx-mode, typescript-mode, rust-mode, and php-mode)
+ Made *eww* popups for dash docsets larger
+ Renamed set-docset! => set-docsets! (set-docset! is aliased to
  set-docsets!)
+ New +lookup/install-docset alias

modules/lang/php/config.el

@@ -7,6 +7,7 @@
   ;; php+html. Use the .phtml
   (setq php-template-compatibility nil)
 
+  (set-docsets! 'php-mode "PHP" "PHPUnit" "Laravel" "CakePHP" "CodeIgniter" "Doctrine_ORM")
   (set-repl-handler! 'php-mode #'php-boris)
   (set-lookup-handlers! 'php-mode :documentation #'php-search-documentation)
   (set-formatter! 'php-mode #'php-cs-fixer-fix)