New aliases: k for gitk and ka for gitk --all

The latter is alternative for `gitka` bash alias

dotfiles/git-universe/before.gitconfig

   grr = log --graph --full-history --all --color\
         --pretty=tformat:"%x1b[31m%h%x09%x1b[32m%d%x1b[0m%x20%s%x1b[0m"\
         --simplify-by-decoration
+  k = !sh -c \
+      '(which gitk >/dev/null || (echo "gitk not installed" && false)) && gitk'
+  ka = !sh -c \
+       '(which gitk >/dev/null || (echo "gitk not installed" && false)) && gitk --all'
   rb = rebase
   rbi = rebase --interactive
   rmv = remote --verbose