Add multiple-cursors to power-edit bundle.

New bindings in ergonomic bundle:
- "C-S-c C-S-c" -> mc/edit-lines
- "C->" -> mc/mark-next-like-this
- "C-<" -> mc/mark-previous-like-this
- "C-c C-<" -> mc/mark-all-like-this
Merge pull request #172 from senny/multiple-cursors

Add multiple-cursors to power-edit bundle