* Move window close button into shell submenu
IMO actions that affect a session don't belong into the window menu.
* Add window zoom menu item
fixes#234
- Add missing separator after `About`.
- Use `role` instead of deprecated `selector` for menu items
- Add `undo` and `redo` menu items. Both Terminal and iTerm have these.
- Remove indent of the report issue template. The indent ended up in the issue body, which looks weird.
- Add separator after `New Tab`. This is how iTerm does it.