Update editor layout. add delete line button

assets/editor/main.js

@@ -144,6 +144,7 @@
         save:           function () { form.requestSubmit(); },
         undo:           function () { CM.undo(view); view.focus(); },
         redo:           function () { CM.redo(view); view.focus(); },
+        deleteline:     function () { CM.deleteLine(view); view.focus(); },
         bold:           function () { wrap('**', '**', 'bold text'); },
         italic:         function () { wrap('*', '*', 'italic text'); },
         h1:             function () { linePrefix('# '); },
@@ -169,11 +170,6 @@
         dateiso:        function () { insertAtCursor(D.isoDate()); },
         datelong:       function () { insertAtCursor(D.longDate()); },
         movie:          function () { M.run(movieCtx); },
-        wide:           function () {
-            var enabled = !document.body.classList.contains('editor-wide');
-            document.body.classList.toggle('editor-wide', enabled);
-            sessionStorage.setItem('editor-wide', enabled ? '1' : '0');
-        },
     };
 
     // Wiki link button: drop an empty [[]] at the cursor and open the `[[`