Improve save/load aliases

When `git load` is invoked it will check if the subject of the `HEAD`
commit message is `temp!`, if it is when the commit will be reset,
otherwise an error message is output and the commit remains untouched.

README.md

@@ -16,7 +16,7 @@ than remember the plumbing term of a specific command.
 * `name` the name of the current branch.
 * `last` the name of the last branch checked out before the current branch.
 * `checkout-last` checkout the last branch, shorthand for
-  `git checkout ``git last`` `.
+  `git checkout $(git last)`.
 * `publish` push and set the tracking branch of a local branch to origin,
   shorthand for `git push -u origin <branch>`.
 * `unpublish` delete a remote branch, shorthand for `git push origin :<branch>`.