Dan Villiom Podlaski Christiansen
rename gdown/gup to next/previous and make them update after their output
gdown/gup refer to the customary order in log output rather than concepts; as such, it may be confusing to the user. Previous and next, however, imply a clear parent/child relationship. We retain the previous names as aliases.
In addition, print the changeset we're updating to first; in the sense, a user will see the output *before* any Mercurial fires up any merge tools, and the output will appear more consistent with most other commands that also update, and commonly do so as their last step.