cmdutil: use named arguments for changeset_templater.__init__ This will make the API more extensible and easier to use.

bundle: inline applybundle1() We have now gotten rid of all but one caller, so let's inline it there.

bundle: make applybundle() delegate v1 bundles to applybundle1()

bundle: transpose transaction scope with bundle type switch This moves the transaction with-statements outside of the per-bundle-version switches, so the next patch will be a little simpler.