paper: show current revision on file log page Most of the pages in paper (and coal) style show the current revision and its branch, tags and bookmarks. Let's also show all this on file log page.

merge.applyupdates: extend action queues with ones returned from mergestate These queues will always be empty at the moment -- we're going to fill them up in upcoming patches.

mergestate: add a method to compute actions to perform on dirstate We're going to use this to extend the action lists in merge.applyupdates. The somewhat funky return value is to make passing this dict directly into recordactions easier. We're going to exploit that in an upcoming patch.