comments: add scores, rework comment menu.

* Add comment scores.
* Rework voting buttons so that you can click the upvote/downvote
  buttons to toggle votes.
* Hide the edit, delete, undelete, and report buttons behind a popup menu.
* Show the upvote/downvote/reply buttons to logged out users. Redirect
  them to the login page instead.

app/javascript/src/javascripts/utility.js

@@ -1,4 +1,5 @@
 import Rails from '@rails/ujs';
+import { hideAll } from 'tippy.js';
 
 let Utility = {};
 
@@ -70,6 +71,9 @@ Utility.dialog = function(title, html) {
   $dialog.find("form").on("submit.danbooru", function() {
     $dialog.dialog("close");
   });
+
+  // XXX hides the popup menu when the Report comment button is clicked.
+  hideAll({ duration: 0 });
 }
 
 Utility.keydown = function(keys, namespace, handler, selector = document) {

app/javascript/src/styles/base/020_base.scss

@@ -103,7 +103,7 @@ menu {
     padding: 0;
   }
 
-  li {
+  > li {
     margin: 0;
     padding: 0 0.2em;
     display: inline;

app/javascript/src/styles/common/messages.scss

@@ -31,7 +31,7 @@ div.list-of-messages {
       flex: 1;
 
       menu {
-        li {
+        > li {
           padding: 0;
           margin-right: 1.5em;
         }