Add xz and lzma support to dired-tar.el

Add xz and lzma support to dired-tar.el

	* dired-tar.el (dired-tar-compress-with): Add lzma and xz
	  (dired-tar-lzma-extension): New.
	  (dired-tar-xz-extension): New.
	  (dired-tar-lzma-command): New.
	  (dired-tar-xz-command): New.
	  (dired-tar-unlzma-command): New.
	  (dired-tar-unxz-command): New.
	  (dired-tar-pack): Handle xz and lzma as well.
	  (dired-tar-lzma-tarfile-regexp): New.
	  (dired-tar-xz-tarfile-regexp): New.
	  (dired-tar-unpack): Handle xz and lzma as well.
	  (dired-tar-pack-unpack): Update doc string to
	  mention xz and lzma.

Signed-off-by: Steve Youngs <steve@sxemacs.org>