Update editor layout. add delete line button

assets/editor/main.html

@@ -6,7 +6,6 @@
 {{define "content"}}
 <script>
     document.body.classList.add('edit-mode');
-    if (sessionStorage.getItem('editor-wide') === '1') document.body.classList.add('editor-wide');
 </script>
 <form id="edit-form" class="edit-form" method="POST" action="{{.PostURL}}">
     {{if ge .SectionIndex 0}}<input type="hidden" name="section" value="{{.SectionIndex}}">{{end}}
@@ -45,6 +44,7 @@
         </span>
         <button type="button" class="btn btn-tool" data-action="quote"     data-key="Q" title="Blockquote (Q)">&gt;</button>
         <button type="button" class="btn btn-tool" data-action="hr"        data-key="R" title="Horizontal rule (R)">---</button>
+        <button type="button" class="btn btn-tool" data-action="deleteline" data-key="Y" title="Delete line (Y)">⌦</button>
         <span class="toolbar-sep"></span>
         <span class="dropdown">
             <button type="button" class="btn btn-tool dropdown-toggle" title="Table (T)">T▾</button>
@@ -72,8 +72,6 @@
                 <button type="button" class="btn btn-tool btn-block" data-action="movie" data-key="V" title="Import movie (V)">Import movie</button>
             </div>
         </span>
-        <span class="toolbar-sep"></span>
-        <button type="button" class="btn btn-tool" data-action="wide"      data-key="Z" title="Toggle wide mode (Z)">⇔</button>
     </div>
     <div id="editor" class="editor-cm"></div>
     <textarea name="content" id="editor-content" hidden>{{.RawContent}}</textarea>