Better "svn list" handling

Better "svn list" handling

* svn2svn/svnclient.py (list, _parse_svn_list_xml): Add a tag for
proper "svn list --xml" handling.
* svn2svn/run/svn2svn.py: Remove get_svn_dirlist() in favor of using
svnclient.list(). Replace all usages of run_svn("svn list") with
svnclient.list(), which eliminates all hacky .split("\n") cases.

* svn2svn/run/svn2svn.py (verify_commit): Move unconditioned "OK"
ui.status line behind an else, so that "OK" message isn't
incorrectly logged when "FAIL" message is logged.