clean-tree should resolve conflicts

[Jelmer Vernooij]

"bzr clean-tree" can remove files that are in conflicts. When it does this, it should resolve the relevant conflicts. E.g.:

blodeuwedd:~/src/breezy.old/unstable% bzr clean-tree
debian/changelog.moved
debian/control.moved
debian/rules.moved
Are you sure you wish to delete these? ([y]es, [n]o): yes
deleting paths:
  debian/changelog.moved
  debian/control.moved
  debian/rules.moved
brz: warning: some compiled extensions could not be loaded; see ``brz help missing-extensions``
blodeuwedd:~/src/breezy.old/unstable% bzr st
conflicts:
  Conflict adding file debian/changelog. Moved existing file to debian/changelog.moved.
  Conflict adding file debian/control. Moved existing file to debian/control.moved.
  Conflict adding file debian/rules. Moved existing file to debian/rules.moved.
brz: warning: some compiled extensions could not be loaded; see ``brz help missing-extensions``
blodeuwedd:~/src/breezy.old/unstable% bzr resolved
0 conflicts auto-resolved.
Remaining conflicts:
Conflict adding file debian/changelog. Moved existing file to debian/changelog.moved.
Conflict adding file debian/control. Moved existing file to debian/control.moved.
Conflict adding file debian/rules. Moved existing file to debian/rules.moved.