Move EditorCommand helpers elsewhere

RootView and Editor now have helpers that support
binding events to callbacks, binding a callback to
all current and future editors, and replacing the
selected text via a transforming callback.

src/app/editor.coffee

@@ -965,3 +965,20 @@ class Editor extends View
     @find('pre.line.cursor-line').removeClass('cursor-line')
     if @getSelection().isSingleScreenLine()
       @find("pre.line:eq(#{screenRow})").addClass('cursor-line')
+
+  bindToKeyedEvent: (key, event, callback) ->
+    binding = {}
+    binding[key] = event
+    window.keymap.bindKeys '.editor', binding
+    @on event, =>
+      callback(this, event)
+
+  replaceSelectedText: (replaceFn) ->
+    selection = @getSelection()
+    return false if selection.isEmpty()
+
+    text = replaceFn(@getTextInRange(selection.getBufferRange()))
+    return false if text is null or text is undefined
+
+    @insertText(text, select: true)
+    true

src/app/root-view.coffee

@@ -232,3 +232,10 @@ class RootView extends View
 
   saveAll: ->
     editor.save() for editor in @getEditors()
+
+  eachEditor: (callback) ->
+    for editor in @getEditors()
+      callback(editor)
+
+    @on 'editor-open', (e, editor) ->
+      callback(editor)