evolve: handle case when newnode can be None while continuing evolve There can be case when `hg evolve --continue` is run, when working directory is clean and there is nothing to be included in the new commit. Let's make sure we handle such cases correctly and obsolete the node which is evolved with parent of wdir as successor. This is same as what rebase does.

tests: add tests for `hg evolve --continue` This patch adds a new test file containing tests for `hg evolve --continue`. The test file still does not contains all the tests related to `hg evolve --continue` as one of the case is broken which needs to be fixed first. The case is when resolving a conflicting evolve results in empty wdir. Next patch will fix the traceback and then a later patch will add more tests.

merge with stable

CHANGELOG: add an entry about resolve showing how to continue evolve

test: explicitly run HGEDITOR shell command with `sh` Otherwise Windows pops up the "What program do you want to use to open this?" dialog.

test: conditionalize blackbox output for Windows

branching: merge with stable

compat: add wrapper for logcmdutil functions These classes and functions were bulk-renamed at hg c8e2d6ed1f9e.

evolve: store the revs to be processed in the evolvestate This will help us in getting a full functional `hg evolve` where `hg evolve --continue` does not only continue one changeset.

evolve: store the replacements in the evolvestate This will greatly help when we will be implementing `hg evolve --abort`.