Add symlink method to util.opener.
Differences from os.symlink:
- the symlink name is relative to the opener base directory
- if a file with that name already exists, it's removed
- if necessary, parent directories are created
- if the system (OS or filesystem) doesn't support symlinks, a
regular file is created. Its contents are the symlink target.
adding empty-file
adding large-file
adding another-file
removing empty-file
removing large-file
recording removal of large-file as rename to another-file (99% similar)
% comparing two empty files caused ZeroDivisionError in the past
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding another-empty-file
removing empty-file
adding large-file
adding tiny-file
adding small-file
removing large-file
removing tiny-file
recording removal of tiny-file as rename to small-file (82% similar)