Add pf

Now that --force-with-lease is a thing, we can have a shortmap that does
something sane rather than blowing changes away.

* shortmaps (pf): Add shortmap.

shortmaps

@@ -34,6 +34,7 @@ Mu _git_submodule :submodule update --recursive
 MP _git_submodule :submodule update --remote --recursive
 p _git_push :push
 pd- : |ref="$( git rev-parse --symbolic-full-name @{-1} )"; git push "${1:-origin}" :"${ref#refs/heads/*}"
+pf _git_push :push --force-with-lease
 pu _git_push :push --set-upstream
 P _git_pull :pull
 Pr _git_pull :pull --rebase=preserve