merge with stable

histedit: delete all non-actionclass related code Now that all actions have been migrated to the class format, we can delete all the unnecessary code that supported the old function format.

histedit: improve roll action integration with fold Previously the fold action would inspect it's class to figure out if it was a rollup or not. This was hacky. Now that finishfold is inside the fold class, let's modify it to check a function (which roll can override) to determine if it should be prompting for a commit message.

histedit: move finishfold into fold class Let's move the finishfold function into the fold class so we can modify it from the roll class more easily.

histedit: convert fold/roll actions into a class This converts the fold/roll actions into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness. The tests changed for two reasons: 1) We get a new 'empty changeset' warning because we now warn more consistently between normal histedit and --continue about commits disappearing. 2) Previously we were not putting the histedit-source extra field on the temporary fold commit during normal runs, but we were on --continue runs. By unifying these code paths we now consistently put histedit-source on the temporary fold commit, which changes some of the hashes in the backup bundles.

histedit: convert edit action into a class This converts the edit action into a histeditclass instance, as part of an ongoing effort to refactor histedit for maintainability and robustness.