git-svn: add a generic tree traversal to fetch SVN properties

git-svn: add a generic tree traversal to fetch SVN properties

	* git-svn.perl (&traverse_ignore): Remove.
	(&prop_walk): New.
	(&cmd_show_ignore): Use prop_walk.

[ew: This will ease the implementation of the `create-ignore',
     `propget', and `proplist' commands]

Signed-off-by: Benoit Sigoure <tsuna@lrde.epita.fr>
Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>