[PATCH] 'svn patch' should remove empty dir

Hi!

Puh, 363 lines added. That's the biggest patch I've written so far. Sad
to think that once we have implemented git diff format this code will be
obsolute :).

Reviews welcome!

[[[
Make 'svn patch' able to remove dirs beeing empty after patching, taken
into account both versioned and unversioned files and dirs.

* subversion/tests/cmdline/patch_tests.py
  (patch_remove_empty_dir): New.
  (test_list): Add new test.

* subversion/libsvn_client/patch.c
  (status_baton): New.
  (find_existing_children, is_dir_empty,
    add_target_to_hash_keyed_by_parent_dir, is_dir_empty,
    sort_compare_nr_of_path_elements,
    maybe_condense_deleted_targets): New functions
  (apply_patches): Call maybe_condense_deleted_targets(). Check if a
    target has a patch associated with it before calling
    svn_diff__close_patch() since we're creating targets to delete dirs
    and those have no associated patch.

Patch by: Daniel Näslund <daniel{_AT_}longitudo.com>
Review by: julianf, stsp, neels
]]]

What target fields must be set for the parent dir target? I've just set
deleted, abs_path and deleted. May be a bit hard to maintain. Would be
better with a central initialize_basic_target() func.

In find_existing_children() I've said that if a path has text_status
svn_wc_status{none,deleted} or is the name of the parent_dir we'll
ignore it, all else states means that we have a file or dir at the path.

I haven't taken file externals into account. If a patch says that a
target should be removed I'm assuming the user knows what they're doing.

Daniel