tig: Shorten length of author in commit list
tig: Shorten length of author in commit list

Most names fit within 16 characters, and most that don’t can still be
uniquely identified by them. Since this view is more for an overview,
affording more space for displaying refs and commit subjects is worth
this trade-off.

amarshall/dotfiles,amarshall/dotfiles,amarshall/dotfiles,amarshall/dotfiles