Change icon and group icons

[andreavuolo]

I would like to have to opportunity to change the icon in the menu bar as an extra feature.

Moreover I would like to have the opportunity to add a group (folder) item in the menu bar, once the mouse is hover or with a click I can see the items that are inside. The counter of notifications should sum the notifications of the app inside the group.
I say this because I have two app to manage mails and I want just one icon in the menu bar