message: Register recently opened/saved .petmate to the OS
  This will support opening recent files from the Dock/JumpList
  Still need Open Recents.. in the menu and would be nice if the
  Recents tab in Finder would also work.
  for
diff: @@ -169,6 +169,7 @@ export const saveWorkspace = (filename: string, screens: number[], getFramebufBy
  })
  try {
  fs.writeFileSync(filename, content, 'utf-8');
  + electron.remote.app.addRecentDocument(filename);
  }
  catch(e) {
  alert(`Failed to save file '${filename}'!`)
  @@ -180,6 +181,7 @@ export const loadWorkspace = (filename: string, dispatch: (thunk: RootStateThunk
  const content = fs.readFileSync(filename, 'utf-8')
  const c = JSON.parse(content)
  dispatch(workspace.load(c));
  + electron.remote.app.addRecentDocument(filename);
  }
  catch(e) {
  console.error(e)
  