Change Editor.proto.split method to use new RootView.proto.addPane method.

RootView.proto.addPane takes a view to add, a sibling to add it next to, an axis along which to add (row or column), and a side (before or after)

src/app/editor.coffee

@@ -468,15 +468,10 @@ class Editor extends View
   splitDown: ->
     @split('column', 'after')
 
-  split: (axis, insertMethod) ->
-    unless @parent().hasClass axis
-      container = $$ -> @div class: axis
-      container.insertBefore(this).append(this.detach())
-
+  split: (axis, side) ->
+    return unless rootView = @rootView()
     editor = new Editor(@getEditorState())
-    this[insertMethod](editor)
-    @rootView().adjustSplitPanes()
-    editor
+    rootView.addPane(editor, this, axis, side)
 
   remove: (selector, keepData) ->
     return super if keepData

src/app/root-view.coffee

@@ -78,6 +78,15 @@ class RootView extends View
       editor.appendTo(@panes)
       editor.focus()
 
+
+  addPane: (view, sibling, axis, side) ->
+    unless sibling.parent().hasClass(axis)
+      container = $$ -> @div class: axis
+      container.insertBefore(sibling).append(sibling.detach())
+    sibling[side](view)
+    @adjustSplitPanes()
+    view
+
   adjustSplitPanes: (element = @panes.children(':first'))->
     if element.hasClass('row')
       totalUnits = @horizontalGridUnits(element)