Use single click to toggle sidebar on/off

Ref #341.

assets/javascripts/views/layout/resizer.coffee

@@ -1,10 +1,12 @@
 class app.views.Resizer extends app.View
   @className: '_resizer'
+  @attributes:
+    title: 'Click to toggle sidebar on/off'
 
   @events:
     dragstart: 'onDragStart'
     dragend: 'onDragEnd'
-    dblclick: 'onDblClick'
+    click: 'onClick'
 
   @isSupported: ->
     'ondragstart' of document.createElement('div') and !app.isMobile()
@@ -32,7 +34,7 @@ class app.views.Resizer extends app.View
       app.appCache?.updateInBackground()
     return
 
-  onDblClick: (event) ->
+  onClick: ->
     app.document.toggleSidebar(save: true)
     return
 

assets/stylesheets/components/_sidebar.scss

@@ -53,6 +53,7 @@
     background: $headerBackground;
     border-right: 1px solid $headerBorder;
     width: 8px;
+    cursor: pointer;
 
     &:before {
       content: '';