new preferences dialog

New preferences dialog with many new options:

  • enable/disable check for updates (which enable/disable pamac-tray)
  • hide or not the tray icon when no update available
  • new menu to choose upgrades to ignore
  • official repos tab is hidden when pacman-mirrorlist is not installed (compatibility whith Archlinux)
  • new button to refresh mirrors list
  • AUR support disable if yaourt is not installed
  • enable/disable check updates from AUR
  • enable/disable confirmation when building packages (--noconfirm)