evolve: deprecate gup and gdown aliases This is done in an effort to clean up the UI of evolve.

evolve: add function to deprecate an alias When cleaning up the UI for evolve we will deprecate old aliases, but still want them to work for a while. This is a helper function that will be called during the extension setup and has the ability map an old alias to a new or canonical one.

evolve: downcase first word in module doc This makes the output of hg help consistent with the other extensions.