Make the post versions more like the old format

- "Current" is now most like the old format
-- It is therefore now the default for post versions
- Only show the actual edits in their own column
- Show the current state at that version in another column
- On the "previous" view, don't double-show full list of tags for
  the first post versions, so leave edits blank

app/javascript/src/styles/base/040_colors.css

@@ -89,6 +89,8 @@
 
   --diff-list-added-color: green;
   --diff-list-removed-color: red;
+  --diff-list-obsolete-added-color: darkGreen;
+  --diff-list-obsolete-removed-color: darkRed;
 
   --wiki-page-versions-diff-del-background: #FCC;
   --wiki-page-versions-diff-ins-background: #CFC;
@@ -299,6 +301,8 @@ body[data-current-user-theme="dark"] {
 
   --diff-list-added-color: var(--green-1);
   --diff-list-removed-color: var(--red-1);
+  --diff-list-obsolete-added-color: var(--green-3);
+  --diff-list-obsolete-removed-color: var(--red-3);
 
   --dtext-blockquote-background: var(--grey-3);
   --dtext-blockquote-border: 1px solid var(--grey-4);

app/javascript/src/styles/specific/post_versions.scss

@@ -10,4 +10,19 @@ body.c-post-versions.a-index {
   .advanced-search-link {
     margin: 0 1em;
   }
+
+  ins.diff-obsolete a {
+    color: var(--diff-list-obsolete-added-color);
+    font-weight: bold;
+  }
+
+  del.diff-obsolete a {
+    color: var(--diff-list-obsolete-removed-color);
+    font-weight: bold;
+  }
+
+  td.tags-column,
+  td.edits-column {
+    width: 40%;
+  }
 }