merge: make 'cd' and 'dc' actions store the same arguments as 'm' We're going to treat these conflicts similarly to merge conflicts, and this change to the way we store things in memory makes future code a lot simpler.

merge: stop emptying out 'cd' and 'dc' actions (1) These aren't currently read from anywhere, so emptying this out is pointless. (2) These *will* be read from later in upcoming patches, and not emptying them out will be important then.

rebase: add returning value from pullrebase function So far pullrebase function has always returned None value, no matter what orig function returned. This behaviour made impossible for pull to change returned value from mercurial process (it has always ended with 0 value by default). This patch makes pullrebase returning with returned value from orig.