Add initial editor command super class

This can be extended by extensions targetted
towards acting on text inside the editor and
not contributing any UI

src/extensions/editor-command.coffee

@@ -0,0 +1,33 @@
+module.exports =
+class EditorCommand
+
+  @activate: (rootView) ->
+    keymaps = @getKeymaps()
+    return unless keymaps
+
+    window.keymap.bindKeys '.editor', keymaps
+
+    for editor in rootView.getEditors()
+      @subscribeToEditor(rootView, editor)
+
+    rootView.on 'editor-open', (e, editor) =>
+      @subscribeToEditor(rootView, editor)
+
+  @subscribeToEditor: (rootView, editor) ->
+    keymaps = @getKeymaps(rootView, editor)
+    return unless keymaps
+
+    for key, event of keymaps
+      editor.on event, => @execute(editor, event)
+
+  @alterSelection: (editor, transform) ->
+     selection = editor.getSelection()
+     return false if selection.isEmpty()
+
+     range = selection.getBufferRange()
+     reverse = selection.isReversed()
+     text = transform(editor.getTextInRange(range))
+     return false if text is null or text is undefined
+     editor.insertText(text)
+     selection.setBufferRange(range, {reverse})
+     true