mutt :: updated sidebar configuration
mutt :: updated sidebar configuration

- give it 45 cols width
- add some extra configuration with nice indenting and short path
- add extra sidebar shortcuts to jump to prev/next folder with unread
  messages
- add extra sidebar shortcut to toggle the sidebar's visibility

Signed-off-by: BlackEagle <6c5c99a37e4dd8841971a4b7c7580d6fcba68554@gmail.com>

BlackIkeEagle/dotfiles,BlackIkeEagle/dotfiles,BlackIkeEagle/dotfiles