commit: enable --secret option At the moment, creating secret commits is slightly cumbersome. They can either be created by changing the default commit phase to secret or by doing `hg phase --secret --force`. Both of these make secret commits appear to be like some kind of advanced feature. Secret commits, however, should be a convenient feature for people who want to work on a private branch without affecting anyone else. There should therefore be a prominent and convenient method for creating secret commits. Since the default phase is draft and there is no need to use --force to go from a secret phase to any other phase, this patch intentionally does not add --draft and --public options.