Updated Arch updating Fish functions.

I have uninstalled aura and installed yaourt. I removed the redundant
Syu function and the obsolete Ayu function, and replaced both with the
"Yu" function, (mnemonic: "yaourt update"). It runs yaourt -Syua, which
updates both the standard pacman packages and AUR packages.
Improve "archlog" capture template.

Remove unnecessary :empty-lines 1 specification.