[PATCH] Fix for sparse updates

Hi,

Please find attached a patch to an issue with updating sparse
working copies via 'Update to revision…'.

The first bug causes TSVN to update certain directories in a
sparse working copy fully recursive whereby the folder has
previously been checked out with all contained files being
excluded. To reproduce:

    1. Sparsely check out any repository. The sparse checkout
       needs to contain a directory structure '^/a/b/', where all
       other files are set to excluded (most importantly, all files
       inside 'b/' need to be excluded.
    2. Select 'Update to revision…'
    3. Click 'Choose items…'
    4. Do not modify any checkboxes. Expand the directory '/a',
       but do _not_ expand '/a/b'.
    5. Accept and let TSVN update the working copy.

Expected is that '/a/b' will be updated using the working copy
depth, that is its contents should stay excluded. But in fact,
TSVN will update '/a/b' fully recursive. The issue is fixed by
using working copy depth for directories which have not been
expanded.

This causes new issue where users are now unable to recursively
check out a sparse directory without expanding its children. This
is handled by doing a fully recursive checkout of the folder if
the user has toggled its checkbox (that is unchecked and
re-checked the checkbox).

Thanks and regards
Patrick